[clang] [clang] Enable C++17 relaxed template template argument matching by default (PR #89807)

[Erich Keane via cfe-commits]

erichkeane wrote:

Great, I agree that is the right way forward.  A more complicated flag like that might be cool someday, but not something we need today.

https://github.com/llvm/llvm-project/pull/89807