[llvm] [TypePromotion] Support trunc-to-i1 conditions (PR #216311)

[Vito Kortbeek via llvm-commits]

vkortbeek-gf wrote:

Thanks for catching this and for the concise example. I overlooked the handling of the `nsw` flag. I have a fix and will open a follow-up PR tomorrow after finishing the tests.

https://github.com/llvm/llvm-project/pull/216311