[llvm] [X86] combineConcatVectorOps - add concatenation handling for BITCAST nodes (PR #133913)

[Devon Loehr via llvm-commits]

DKLoehr wrote:

It seems like this is causing a crash when trying to link one of chromium's testing binaries. Unfortunately I'm not sure how to look for a minimal reproduction at the moment, but I can point to a failing build: https://ci.chromium.org/ui/p/chromium/builders/ci/CFI%20Linux%20ToT/45085/overview

https://github.com/llvm/llvm-project/pull/133913