cpu: Add HTM ExecContext API

* initiateHtmCmd(Request::Flags flags)
* getHtmTransactionUid()
* newHtmTransactionUid()
* inHtmTransactionalState()
* getHtmTransactionalDepth()

JIRA: https://gem5.atlassian.net/browse/GEM5-587

Change-Id: I438832a3c47fff1d12d0123425985cfa2150ab40
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/30323
Tested-by: kokoro <noreply+kokoro@google.com>
5 files changed