[llvm] [GlobalISel] Check whether `G_CTLZ` is legal in `matchUMulHToLShr` (PR #126457)

[Shilei Tian via llvm-commits]

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+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
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shiltian wrote:

Yeah, I guess I'm gonna merge as it is. Didn't get the luck with 64 bit as well.

https://github.com/llvm/llvm-project/pull/126457