[llvm] [InstCombine] Add fold combining adjacent extracted bit fields to restore optimization for separate truncations (PR #219598)

[Andreas Jonson via llvm-commits]

https://github.com/andjo403 approved this pull request.

looks good to me but wait for a review from @nikic or @dtcxzyw 

https://github.com/llvm/llvm-project/pull/219598