[clang] [clang] Prefer exact template-template matches in partial ordering (PR #216113)

[Vish Abrams via cfe-commits]

vishvananda wrote:

I added a clang test. LMK if that is in the right place. I also made a request to get it added to the perf tracker. I'll update with results.

https://github.com/llvm/llvm-project/pull/216113