[XRay] ARM 32-bit no-Thumb support in compiler-rt

This is a port of XRay to ARM 32-bit, without Thumb support yet.
This is one of 3 commits to different repositories of XRay ARM port. The
other 2 are:

1. https://reviews.llvm.org/D23931 (LLVM)
2. https://reviews.llvm.org/D23932 (Clang test)

Differential Revision: https://reviews.llvm.org/D23933

llvm-svn: 280890