Meson 0.56.2 and Python39 --> dav1d failing

[Ryan Schmidt]

On Feb 4, 2021, at 11:26, Ken Cunningham wrote:

> wait, I could have missed the issue...if meson is now adding a default argument to all checks that means it can never build anything with the default compilers on <10.10, that would be something we should consider fixing in meson, even if upstream doesn't want to.
> 
> So if testing shows that all builds on 10.7 -10.9 of meson ports are broken, then yeah, that's different, sure.

That sounds like what Craig is saying: that meson is now adding a compiler flag that old compilers don't understand. Meson should check whether a compiler supports a flag before it adds it. We should not be responsible for fixing this; the developers of meson should.