[llvm] [BOLT][AArch64] Run LDR relaxation (PR #165787)

[Paschalis Mpeis via llvm-commits]

https://github.com/paschalis-mpeis commented:

Thanks for adding LDR relaxation, @yozhu, and for the extensive tests!
I left a few nits and a comment around naming.

https://github.com/llvm/llvm-project/pull/165787