[clang] [Clang] Fix ICE in constraint normalization when substituting concept template parameters (PR #184406)

[Younan Zhang via cfe-commits]

https://github.com/zyn0217 commented:

Some nits, otherwise I don't have more comments.

Would be nice if @cor3ntin can have a look because he's the author


https://github.com/llvm/llvm-project/pull/184406