[Mesa-dev] Supporting macOS / XQuartz on master

[Jeremy Huddleston Sequoia]

Hey folks,

I finally had a little bit of time to take a look at mesa and XQuartz for the first time in ~4 years.  I am incredibly impressed that there wasn't more bitrot.  I was expecting a painful few days since I've never looked at meson, but I was able to get it functional relatively quickly.

I have a few pull requests which I'd like to have some eyes on.

These first two are a meson configuration changes to pickup the system libexpat and libunwind (plus a build fix due to bad implicit casting in mesa's libunwind usage).  I'd appreciate someone with meson-fu to look them over and let me know if there's a better way to do this:

https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8501
https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8502

This last one is probably a bit more political as it bumps our C language version from C99 to C11.  This is being done because we make use of timespec_get() which was added to C11.  Using -std=c99 will cause the prototype to be omitted from system headers on strictly compliant systems (eg: macOS) even when the system supports this function.

https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8496

Thanks in advance for looking these over.

--Jeremy