[XRay][AArch64] More staging for tail call support in XRay AArch64 - in compiler-rt

Summary:
This patch provides a trampoline for function tail exit tracing. Still, it's staging because code `1` is passed to the handler function (indicating a normal exit) instead of `2`, which would indicate tail exit. This is so until the logging part of XRay supports tail exits too.
Related: https://reviews.llvm.org/D28947 (LLVM)

Reviewers: dberris, rengolin

Reviewed By: rengolin

Subscribers: aemerson, llvm-commits, iid_iunknown

Differential Revision: https://reviews.llvm.org/D28948

llvm-svn: 293082