OpenAL-Soft fails to compile on some GCC version:
https://travis-ci.com/github/ArthurSonzogni/smk/jobs/318304162
It has regressed likely after:
c83609277b
va_start is defined in:
- <stdarg.h>
- <cstdarg>
The repository is using it from:
- al/error.cpp
- al/filter.cpp
- alc/alu.cpp
- alc/helpers.cpp
- common/alexcpt.cpp
- utils/makemhr/loaddef.cpp
- utils/openal-info.c
This patch is adding its definition in the files missing it:
- common/alexcpt.cpp
- utils/makemhr/loaddef.cpp
- utils/openal-info.c
Bug: https://travis-ci.com/github/ArthurSonzogni/smk/jobs/318304162
