When calling Configure with use64bitall on arm64 macOS, it compiles a test program using clang and an -arch flag that is not followed by anything. Seems like the darwin arch hint when using use64bitall couldn't work with the 'arm' result from uname -p.

Not sure if Apple are to introduce another CPU architecture to their device lineup - but they already did it 2 times. When building this on arm64 macOS, before adding the arm64 arch hint, Configure with use64bitall wouldn't exit, but a rather cryptic clang error would be thrown for an unknown arch name, simply because nothing was passed after the -arch flag.