[clang] [Clang][Sema] Do not add implicit 'const' when matching constexpr function template explicit specializations after C++14 (PR #92449)

[Erich Keane via cfe-commits]

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

Release note, else LGTM

https://github.com/llvm/llvm-project/pull/92449