[llvm] [RISCV] Add late optimization pass for riscv (PR #133256)

[Mikhail R. Gadelha via llvm-commits]

mikhailramalho wrote:

> LGTM, but obviously we need to wait for @preames change to go in first.

He landed it this morning. I'll update the patch description. 

https://github.com/llvm/llvm-project/pull/133256