[llvm] [DAG] canCreateUndefOrPoison - add EXTRACT_SUBVECTOR handling (PR #132745)

[Philip Reames via llvm-commits]

https://github.com/preames commented:

Code is correct, this properly is asserted in SelectionDAG::getNode.  I can't comment on the x86 diffs.

https://github.com/llvm/llvm-project/pull/132745