[llvm] [X86][GISEL] Enable PostLegalize Combiner (PR #174696)

[Evgenii Kudriashov via llvm-commits]

https://github.com/e-kud commented:

I'm not sure, should we add NPM interface? Or should it be still a separate PR for it?

https://github.com/llvm/llvm-project/pull/174696