[llvm] Reland [llvm-ml] Fix RIP-relative addressing for ptr operands (PR #108061)

[Martin Storsjö via llvm-commits]

mstorsjo wrote:

> Seems sensible to me - but @mstorsjo should probably check that this works on the OpenMP build too. (I'm less experienced with that.)

I've verified that the OpenMP object files assemble into bitexact the same thing as before, after this patch, and no asserts are triggered now.

https://github.com/llvm/llvm-project/pull/108061