[PATCH] Fix building against the system portaudio library

[PATCH] Fix building against the system portaudio library

Building against the system portaudio results in this error:

./src/AudioIO.cpp:983: undefined reference to `PaUtil_GetTime'
audacity-AudioIO.o: In function `audacityAudioCallback(void const*, void*,
unsigned long, PaStreamCallbackTimeInfo const*, unsigned long, void*)':
./src/AudioIO.cpp:4630: undefined reference to `PaUtil_GetTime'
collect2: error: ld returned 1 exit status
Makefile:2349: recipe for target 'audacity' failed
make[3]: *** [audacity] Error 1

This is because PaUtil_GetTime is declared as a C symbol in pa_util.h
but is resolved as a C++ symbol at link time.

Audacity fixes this in the local tree with this change:
https://github.com/audacity/audacity/commit/38fd97b8e26060332ab3e9e000a8882326a70ba7

However this is not general enough for the portaudio debian package.

Since PaUtil_GetTime() is the only function causing problems, just copy
over the code where it's used.

[Sebastian Ramacher]: Call clock_gettime directly.

Gbp-Pq: Name 0002-PATCH-Fix-building-against-the-system-portaudio-libr.patch