[AArch64][ARM][X86] Split XRay tests for Linux/macOS

XRay instrumentation works for macOS running on Apple Silicon, but
codegen is untested there. I'm going to make changes affecting this
target, get the XRay tests running on AArch64.

Data sections are going to become slightly different on x86_64 soon.
I do want the tests to be specific about symbol names, so instead of
having test check the common step, bifurcate tests a bit and check
the full symbol names.

As for ARM, XRay is not really supported on iOS at the moment, though
ARM is also really used there with modern phones. Nevertheless, codegen
tests exist and the output is going to change a little, make it easier
to write the special case for iOS.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D145291