[llvm-branch-commits] [clang] Backport: [clang] fix matching of nested template template parameters (PR #130950)

[Erich Keane via llvm-branch-commits]

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

This is an unfortunate and pretty nasty regression that I think we ought to fix.  I am pretty confident that this is low risk as well, so I'm in favor of backporting this.

https://github.com/llvm/llvm-project/pull/130950