[AArch64] Add support for Transactional Memory Extension (TME)
TME is a future architecture technology, documented in
More about the future architectures:
This patch adds support for the TME instructions TSTART, TTEST, TCOMMIT, and
TCANCEL and the target feature/arch extension "tme".
It also implements TME builtin functions, defined in ACLE Q2 2019
Patch by Javed Absar and Momchil Velikov
Differential Revision: https://reviews.llvm.org/D64416