Ports the linux.rseq test and its extensive inline assembly to AArch64. We use compiler-acquired C variable addresses prior to the assembly sequences for simplicity. This should be fine as there are plenty of GPR's and DR handles inputs.
Tested natively and with forthcoming DR rseq mangling changes; separated to keep diffs smaller. These tests will be enabled in the PR that adds DR handling.
Issue: #4316 (closed)