strange linking issue with libjack on armv6hf-musl

[Chris Brannon <ch...@the-brannons.com>]

Hello,
Earlier today, I built the espeak package and its dependencies for my
armv6hf-musl system, a Raspberry Pi.
On the Pi, I tried to build a program that uses espeak.
I got a bunch of errors like the following:

/lib/libjack.so.0: undefined reference to `vtable for
std::basic_streambuf<char, std::char_traits<char> >@GLIBCXX_3.4'
/lib/libjack.so.0: undefined reference to
`__cxa_allocate_exception@CXXABI_1.3'
/lib/libjack.so.0: undefined reference to
`std::basic_ios<char,
std::char_traits<char> >::init(std::basic_streambuf<char, std::char_traits<char> >*)@GLIBCXX_3.4'
*snip more like this*
/lib/libjack.so.0: undefined reference to
`std::string::append(std::string const&)@GLIBCXX_3.4'
*and more of the same*

espeak links against libjack indirectly, via portaudio.

Here's a very tiny program that reproduces the problem:

#include <espeak/speak_lib.h>

int main(void) {
  int rate = 	espeak_Initialize(AUDIO_OUTPUT_PLAYBACK, 50, NULL, 0);
  return 0;
}

It should compile with gcc example.c -lespeak

I also see the same errors when trying to build an example program from
the portaudio distribution.

I made a package of my original program that uses espeak, and that built
just fine with xbps-src -a armv6hf-musl on an x86_64 machine.
So the question is, why does libjack give all these undefined reference
errors when I'm building natively on the Pi, but not when
cross-compiling via xbps-src?
My suspicion is that it has something to do with the libjack package
being cross-compiled originally, but I don't know enough about cross
compilation to prove it.

-- Chris