[clang] [clang] check constant template parameters in dependent contexts (PR #159463)

[Erich Keane via cfe-commits]

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

I think this makes sense, it seems to do as described at least.  I'm not sure WHAT, but it feels like we could/should do a better job with some demonstrative tests though.

https://github.com/llvm/llvm-project/pull/159463