Build on macOS 13 for 12 and lower

[TheSin-]

To build on macOS 13 for 12 or lower, you need to add

[env]
ac_cv_func_mkfifoat=no
ac_cv_func_mknodat=no

to the conan default config. This is due to libSystem changes in 13 that are not present previously.

This might need to be added to conan upstream, but I wanted to at least post it here for current builds since we are version locked to conan 1.56 currently anyhow.

These settings won't hurt older version of macOS, so they could be set to macOS only. I also recommend setting them globally, right now I believe this will only affect cpython, but if other depends link against libSystem and detect those symbols it'll also case issues at runtime on older macOS releases.