[clang] [llvm] [Clang][CodeGen][X86] Fix crash on __int128 bit-field access units (PR #216777)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

> No against reverting, but is the problem just missing a `-fclang-abi-compat=23`? I think it's also ok to commit a seperate patch for it.

+1; I think a revert is fine to give breathing room but I think fixing it forward to give an ABI compat flag is also fine if done quickly enough

> This change broke several CIR ABI tests.

Are there bots that should have reported that breakage? The only report that I can see is for https://lab.llvm.org/buildbot/#/builders/190/builds/48978

https://github.com/llvm/llvm-project/pull/216777