ARM64: Enable implicit suspend checks and madvise()...
... away the alternate signal stack in the entrypoint.
Also fix 706-checker-scheduler to check the correct LDR.
During development of implicit suspend checks, the LDR
was emitted in the loop header but the final version
emits it at the back edge.
Also make `GenerateSuspendCheck()` consistently emit
the branch to `successor` if not null.
Test: run-gtests.sh
Test: testrunner.py --target --64 --optimizing
Bug: 38383823
Bug: 209235730
Change-Id: Ie3e2513d1b22522219f0f8a4ab8bcfd8921e8cdf
13 files changed