mono 6.12.0.182 fails to build on macOS Ventura

[fxcoudert]

Steps to Reproduce

1. Build mono 6.12.0.182 from source as part of Homebrew on macOS Ventura (Apple Silicon):

brew install -svd mono

Current Behavior

Failure to compile, with the following error message:

mono-threads-mach-helper.c:63:8: error: no member named 'class' in 'struct objc_super'
          super.class = nsobject;

Expected Behavior

On previous macOS Monterey, the same build was successful.

On which platforms did you notice this

[X] macOS
[ ] Linux
[ ] Windows

Version Used: macOS 13.0 (released version)

[lambdageek]

It's an Xcode 14 issue, I think. We need to bring over dotnet/runtime#76433

[lambdageek]

/cc @akoeplinger