[XRay] ARM 32-bit no-Thumb support in Clang

Just a test for now, adapted from x86_64 tests of XRay.
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/D23933 (compiler-rt)

Differential Review: https://reviews.llvm.org/D23932

llvm-svn: 280889