[X86] Rename X86_CPU_TYPE_COMPAT_ALIAS/X86_CPU_TYPE_COMPAT/X86_CPU_SUBTYPE_COMPAT macros. NFC

Remove _COMPAT. Drop the ARCHNAME. Remove the non-COMPAT versions
that are no longer needed.

We now only use these macros in places where we need compatibility
with libgcc/compiler-rt. So we don't need to call out _COMPAT
specifically.