New issue by jnbr on void-packages repository

https://github.com/void-linux/void-packages/issues/15631

Description:
On musl systems, pulseaudio's `pa_threaded_mainloop` deadlocks.
This is used by gstreamer's pulseaudio sink and thus affects many packages.

Example code to trigger the bug: https://gist.github.com/jnbr/e622b3cf5020afdf28b68dd3195ded16

And backtrace:

```
Thread 4 (LWP 26160):
#0  0x00007ffff7f8c15a in __syscall6 (a6=<optimized out>, a5=<optimized out>, a4=<optimized out>, a3=<optimized out>, a2=<optimized out>, a1=<optimized out>, n=202) at ./arch/x86_64/syscall_arch.h:59
#1  syscall (n=n@entry=202) at src/misc/syscall.c:20
#2  0x00007ffff7ca4e98 in g_cond_wait_until (end_time=<optimized out>, mutex=0x555555568e60, cond=0x555555568e68) at ../glib/gthread-posix.c:1470
#3  g_cond_wait_until (cond=0x555555568e68, mutex=0x555555568e60, end_time=<optimized out>) at ../glib/gthread-posix.c:1443
#4  0x00007ffff7d21561 in g_async_queue_pop_intern_unlocked (queue=queue@entry=0x555555568e60, wait=wait@entry=1, end_time=end_time@entry=273715104932) at ../glib/gasyncqueue.c:422
#5  0x00007ffff7d21732 in g_async_queue_timeout_pop (queue=0x555555568e60, timeout=<optimized out>) at ../glib/gasyncqueue.c:545
#6  0x00007ffff7cc89c9 in g_thread_pool_wait_for_new_pool () at ../glib/gthreadpool.c:168
#7  g_thread_pool_thread_proxy (data=<optimized out>) at ../glib/gthreadpool.c:365
#8  0x00007ffff7ccc14d in g_thread_proxy (data=0x5555557914a0) at ../glib/gthread.c:805
#9  0x00007ffff7fb5a21 in start (p=<optimized out>) at src/thread/pthread_create.c:195
#10 0x00007ffff7fc319b in __clone () at src/thread/x86_64/clone.s:22
Backtrace stopped: frame did not save the PC

Thread 3 (LWP 26159):
#0  0x00007ffff7f8c15a in __syscall6 (a6=<optimized out>, a5=<optimized out>, a4=<optimized out>, a3=<optimized out>, a2=<optimized out>, a1=<optimized out>, n=202) at ./arch/x86_64/syscall_arch.h:59
#1  syscall (n=n@entry=202) at src/misc/syscall.c:20
#2  0x00007ffff7ca42df in g_cond_wait (cond=cond@entry=0x555555772650, mutex=mutex@entry=0x555555772648) at ../glib/gthread-posix.c:1422
#3  0x00007ffff7436b8b in gst_base_sink_wait_preroll (sink=sink@entry=0x555555772520 [GstBaseSink|sink]) at ../libs/gst/base/gstbasesink.c:2370
#4  0x00007ffff74b959b in gst_audio_base_sink_render (bsink=0x555555772520 [GstBaseSink|sink], buf=0x55555578c7e0 [None]) at ../gst-libs/gst/audio/gstaudiobasesink.c:2151
#5  0x00007ffff7431e2a in gst_base_sink_chain_unlocked.isra.0.lto_priv.0 (basesink=0x555555772520 [GstBaseSink|sink], obj=0x55555578c7e0, is_list=0, pad=<optimized out>) at ../libs/gst/base/gstbasesink.c:3649
#6  0x00007ffff74349d0 in gst_base_sink_chain_main (basesink=0x555555772520 [GstBaseSink|sink], pad=<optimized out>, obj=0x55555578c7e0, is_list=0) at ../libs/gst/base/gstbasesink.c:3775
#7  0x00007ffff7e8a47f in gst_pad_chain_data_unchecked (pad=pad@entry=0x555555768390 [GstPad|sink], type=type@entry=4112, data=data@entry=0x55555578c7e0) at ../gst/gstpad.c:4327
#8  0x00007ffff7e8af01 in gst_pad_push_data (pad=pad@entry=0x555555768140 [GstPad|src], type=type@entry=4112, data=data@entry=0x55555578c7e0) at ../gst/gstpad.c:4583
#9  0x00007ffff7e8b476 in gst_pad_push (pad=pad@entry=0x555555768140 [GstPad|src], buffer=0x55555578c7e0 [None]) at ../gst/gstpad.c:4702
#10 0x00007ffff742e285 in gst_base_src_loop (pad=0x555555768140 [GstPad|src]) at ../libs/gst/base/gstbasesrc.c:2974
#11 0x00007ffff7e546df in gst_task_func (task=0x55555578c050 [GstTask|source:src]) at ../gst/gsttask.c:328
#12 0x00007ffff7cc8924 in g_thread_pool_thread_proxy (data=<optimized out>) at ../glib/gthreadpool.c:308
#13 0x00007ffff7ccc14d in g_thread_proxy (data=0x5555555b4de0) at ../glib/gthread.c:805
#14 0x00007ffff7fb5a21 in start (p=<optimized out>) at src/thread/pthread_create.c:195
#15 0x00007ffff7fc319b in __clone () at src/thread/x86_64/clone.s:22
Backtrace stopped: frame did not save the PC

Thread 2 (LWP 26158):
#0  __syscall_cp_c (nr=202, u=140737331214116, v=128, w=0, x=0, y=0, z=0) at ./arch/x86_64/syscall_arch.h:61
#1  0x00007ffff7fb3ce7 in __timedwait_cp (addr=addr@entry=0x7ffff6a23724, val=val@entry=0, clk=clk@entry=0, at=at@entry=0x0, priv=128, priv@entry=1) at src/thread/__timedwait.c:31
#2  0x00007ffff7fb3dee in __timedwait (addr=addr@entry=0x7ffff6a23724, val=val@entry=0, clk=clk@entry=0, at=at@entry=0x0, priv=priv@entry=1) at src/thread/__timedwait.c:48
#3  0x00007ffff7fb6a4d in pthread_mutex_timedlock_pi (at=0x0, m=<optimized out>) at src/thread/pthread_mutex_timedlock.c:33
#4  __pthread_mutex_timedlock (m=<optimized out>, at=at@entry=0x0) at src/thread/pthread_mutex_timedlock.c:50
#5  0x00007ffff7fb680c in __pthread_mutex_lock (m=m@entry=0x555555772f40) at src/thread/pthread_mutex_lock.c:9
#6  0x00007ffff72a39fe in pa_mutex_lock (m=m@entry=0x555555772f40) at pulsecore/mutex-posix.c:90
#7  0x00007ffff730749d in poll_func (ufds=<optimized out>, nfds=3, timeout=10, userdata=0x555555772f40) at pulse/thread-mainloop.c:71
#8  0x00007ffff72f8db9 in pa_mainloop_poll (m=m@entry=0x5555557748a0) at pulse/mainloop.c:824
#9  0x00007ffff72f943f in pa_mainloop_iterate (m=0x5555557748a0, block=<optimized out>, retval=0x0) at pulse/mainloop.c:926
#10 0x00007ffff72f94f0 in pa_mainloop_run (m=0x5555557748a0, retval=retval@entry=0x0) at pulse/mainloop.c:945
#11 0x00007ffff73073d9 in thread (userdata=0x555555772ee0) at pulse/thread-mainloop.c:101
#12 0x00007ffff72a4888 in internal_thread_func (userdata=0x5555557749c0) at pulsecore/thread-posix.c:81
#13 0x00007ffff7fb5a21 in start (p=<optimized out>) at src/thread/pthread_create.c:195
#14 0x00007ffff7fc319b in __clone () at src/thread/x86_64/clone.s:22
Backtrace stopped: frame did not save the PC

Thread 1 (LWP 26154):
#0  __cp_end () at src/thread/x86_64/syscall_cp.s:29
#1  0x00007ffff7fb4a36 in __syscall_cp_c (nr=202, u=140737488347268, v=128, w=<optimized out>, x=<optimized out>, y=<optimized out>, z=0) at src/thread/pthread_cancel.c:33
#2  0x00007ffff7fb3ce7 in __timedwait_cp (addr=addr@entry=0x7fffffffe084, val=val@entry=2, clk=clk@entry=0, at=at@entry=0x0, priv=128, priv@entry=1) at src/thread/__timedwait.c:31
#3  0x00007ffff7fb4e91 in __pthread_cond_timedwait (c=0x555555772f80, m=0x555555772f40, ts=ts@entry=0x0) at src/thread/pthread_cond_timedwait.c:100
#4  0x00007ffff7fb55c7 in pthread_cond_wait (c=<optimized out>, m=<optimized out>) at src/thread/pthread_cond_wait.c:5
#5  0x00007ffff72a3e17 in pa_cond_wait (c=<optimized out>, m=<optimized out>) at pulsecore/mutex-posix.c:139
--Type <RET> for more, q to quit, c to continue without paging--
#6  0x00007ffff7307b28 in pa_threaded_mainloop_wait (m=0x555555772ee0) at pulse/thread-mainloop.c:216
#7  0x00007ffff733bd28 in gst_pulsering_set_corked (pbuf=pbuf@entry=0x55555577a070 [GstPulseRingBuffer|pulseringbuffer0], corked=corked@entry=1, wait=wait@entry=1) at ../ext/pulse/pulsesink.c:1137
#8  0x00007ffff733d54b in gst_pulseringbuffer_pause (buf=0x55555577a070 [GstAudioRingBuffer|pulseringbuffer0]) at ../ext/pulse/pulsesink.c:1268
#9  0x00007ffff7491039 in gst_audio_ring_buffer_pause_unlocked (buf=buf@entry=0x55555577a070 [GstAudioRingBuffer|pulseringbuffer0]) at ../gst-libs/gst/audio/gstaudioringbuffer.c:1060
#10 0x00007ffff74947a0 in gst_audio_ring_buffer_pause (buf=0x55555577a070 [GstAudioRingBuffer|pulseringbuffer0]) at ../gst-libs/gst/audio/gstaudioringbuffer.c:1103
#11 0x00007ffff74b62fe in gst_audio_base_sink_change_state (element=0x555555772520 [GstElement|sink], transition=<optimized out>) at ../gst-libs/gst/audio/gstaudiobasesink.c:2454
#12 0x00007ffff7338ee3 in gst_pulsesink_change_state (element=0x555555772520 [GstElement|sink], transition=GST_STATE_CHANGE_PLAYING_TO_PAUSED) at ../ext/pulse/pulsesink.c:3265
#13 0x00007ffff7eaa745 in gst_element_change_state (element=element@entry=0x555555772520 [GstElement|sink], transition=transition@entry=GST_STATE_CHANGE_PLAYING_TO_PAUSED) at ../gst/gstelement.c:2952
#14 0x00007ffff7eaae59 in gst_element_set_state_func (element=0x555555772520 [GstElement|sink], state=GST_STATE_PAUSED) at ../gst/gstelement.c:2906
#15 0x00007ffff7ece0e8 in gst_bin_element_set_state (next=GST_STATE_PAUSED, current=GST_STATE_PLAYING, start_time=1990685000 [0:00:01.990685000], base_time=0 [0:00:00.000000000], element=0x555555772520 [GstElement|sink], bin=0x5555557761c0 [GstBin|test-pipeline]) at ../gst/gstbin.c:2605
#16 gst_bin_change_state_func (element=0x5555557761c0 [GstElement|test-pipeline], transition=GST_STATE_CHANGE_PLAYING_TO_PAUSED) at ../gst/gstbin.c:2947
#17 0x00007ffff7e816a7 in gst_pipeline_change_state (element=0x5555557761c0 [GstElement|test-pipeline], transition=GST_STATE_CHANGE_PLAYING_TO_PAUSED) at ../gst/gstpipeline.c:504
#18 0x00007ffff7eaa745 in gst_element_change_state (element=element@entry=0x5555557761c0 [GstElement|test-pipeline], transition=transition@entry=GST_STATE_CHANGE_PLAYING_TO_PAUSED) at ../gst/gstelement.c:2952
#19 0x00007ffff7eaae59 in gst_element_set_state_func (element=0x5555557761c0 [GstElement|test-pipeline], state=GST_STATE_PAUSED) at ../gst/gstelement.c:2906
#20 0x00005555555554f1 in main (argc=1, argv=0x7fffffffe508) at test.c:47
```