[XRay][Arm32] Reduce the portion of the stub and implement more staging for...

[XRay][Arm32] Reduce the portion of the stub and implement more staging for tail calls - in compiler-rt

Summary:
This patch provides more staging for tail calls in XRay Arm32 . When the logging part of XRay is ready for tail calls, its support in the core part of XRay Arm32 may be as easy as changing the number passed to the handler from 1 to 2.
Coupled patch:
- https://reviews.llvm.org/D28673

Reviewers: dberris, rengolin

Reviewed By: dberris, rengolin

Subscribers: llvm-commits, iid_iunknown, aemerson

Differential Revision: https://reviews.llvm.org/D28674

llvm-svn: 293186