[clang] [Clang][Sema] Fix crash when 'this' is used in a dependent class scope function template specialization that instantiates to a static member function (PR #87541)

[Erich Keane via cfe-commits]

erichkeane wrote:

I'm OK with this, but would like @cor3ntin to take another look since he engaged earlier.


https://github.com/llvm/llvm-project/pull/87541