Meson 0.56.2 and Python39 --> dav1d failing

[Ken Cunningham]

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.

Ken