Backport of LoongArch llvmpipe ORCJIT support to 24.2

What does this MR do and why?

This is requesting a backport of LoongArch support in the llvmpipe ORCJIT codepaths for the 24.2 branch. The original changes narrowly missed the 24.2 branching, and are relatively small-sized and only affects this one new hardware platform.

!30599 (merged) is ideally also candidate 24.2 backport material but I'll wait for it to get mainlined first.