New comment by ezag on void-packages repository

https://github.com/void-linux/void-packages/pull/21825#issuecomment-634982388

Comment:
Unfortunatelly I have no idea how to fix cross compilation for following architectures and have disabled them:

- aarch64
- aarch64-musl
- armv7l

Fixes are welcome if anyone is able & interested, `CMakeError.log` output is similar for all failing builds:
```
Performing C SOURCE FILE Test CMAKE_HAVE_LIBC_PTHREAD failed with the following output:
Change Dir: /builddir/PrusaSlicer-version_2.2.0/build/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/make cmTC_161ac/fast && /usr/bin/make  -f CMakeFiles/cmTC_161ac.dir/build.make CMakeFiles/cmTC_161ac.dir/build
make[1]: Entering directory '/builddir/PrusaSlicer-version_2.2.0/build/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_161ac.dir/src.c.o
/builddir/.xbps-PrusaSlicer/wrappers/aarch64-linux-gnu-gcc   -fstack-clash-protection -D_FORTIFY_SOURCE=2 -O2 -march=armv8-a   -I/usr/aarch64-linux-gnu/usr/include -DCMAKE_HAVE_LIBC_PTHREAD -fPIE   -o CMakeFiles/cmTC_161ac.dir/src.c.o   -c /builddir/PrusaSlicer-version_2.2.0/build/CMakeFiles/CMakeTmp/src.c
Linking C executable cmTC_161ac
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_161ac.dir/link.txt --verbose=1
/builddir/.xbps-PrusaSlicer/wrappers/aarch64-linux-gnu-gcc -fstack-clash-protection -D_FORTIFY_SOURCE=2 -O2 -march=armv8-a   -I/usr/aarch64-linux-gnu/usr/include -DCMAKE_HAVE_LIBC_PTHREAD  -Wl,-z,relro -Wl,-z,now -Wl,--as-needed    -L/usr/aarch64-linux-gnu/usr/lib  CMakeFiles/cmTC_161ac.dir/src.c.o  -o cmTC_161ac 
/usr/lib/gcc/aarch64-linux-gnu/9.3.0/../../../../aarch64-linux-gnu/bin/ld: CMakeFiles/cmTC_161ac.dir/src.c.o: in function `main':
src.c:(.text.startup+0x30): undefined reference to `pthread_create'
/usr/lib/gcc/aarch64-linux-gnu/9.3.0/../../../../aarch64-linux-gnu/bin/ld: src.c:(.text.startup+0x38): undefined reference to `pthread_detach'
/usr/lib/gcc/aarch64-linux-gnu/9.3.0/../../../../aarch64-linux-gnu/bin/ld: src.c:(.text.startup+0x40): undefined reference to `pthread_cancel'
/usr/lib/gcc/aarch64-linux-gnu/9.3.0/../../../../aarch64-linux-gnu/bin/ld: src.c:(.text.startup+0x4c): undefined reference to `pthread_join'
collect2: error: ld returned 1 exit status
make[1]: *** [CMakeFiles/cmTC_161ac.dir/build.make:107: cmTC_161ac] Error 1
make[1]: Leaving directory '/builddir/PrusaSlicer-version_2.2.0/build/CMakeFiles/CMakeTmp'
make: *** [Makefile:141: cmTC_161ac/fast] Error 2


Source file was:
#include <pthread.h>

void* test_func(void* data)
{
  return data;
}

int main(void)
{
  pthread_t thread;
  pthread_create(&thread, NULL, test_func, NULL);
  pthread_detach(thread);
  pthread_cancel(thread);
  pthread_join(thread, NULL);
  pthread_atfork(NULL, NULL, NULL);
  pthread_exit(NULL);

  return 0;
}
```