Tests: recognize Xcode 13 linker warning
The linker shipped with Xcode 13 changed the architecture mismatch linker warning into:
ld: warning: ignoring file libfoo.a, building for macOS-x86_64 but attempting to link with file built for macOS-i386The linker shipped with Xcode 13 changed the architecture mismatch linker warning into:
ld: warning: ignoring file libfoo.a, building for macOS-x86_64 but attempting to link with file built for macOS-i386