[compiler-rt][hwasan] Factor out CanUseTaggingAbi() and EnableTaggingAbi()

Simplify InitializeOsSupport() by separating code for detecting and
enabling the tagged address ABI.

Also drop the unnecessary errno checks (regardless of errno value, we
cannot assume that tagging works if the system call failed) and ensure
prctl(PR_SET_TAGGED_ADDR_CTRL) is only called on Android, not on x86
(where arch_prctl(ARCH_ENABLE_TAGGED_ADDR, kTagBits) is used).

Depends on D132544

Differential Revision: https://reviews.llvm.org/D132545