[clang] [Clang] Fixed UnresolvedLookupExpr propagating into the codegen phase (PR #124609)

[Erich Keane via cfe-commits]

erichkeane wrote:

This doesn't quite seem right to me... First, I would expect us to check the declaration context here rather than whether it is in a function template.  

Second, I find myself thinking the `UnresolvedLookupExpr` in a non-dependent context is the actual problem, and we need to figure out how we got there, as that is the big problem.  

https://github.com/llvm/llvm-project/pull/124609