[clang] [analyzer] Fix [[clang::suppress]] for template instantiations (PR #168954)

[Artem Dergachev via cfe-commits]

haoNoQ wrote:

It's actually much weirder than that. Your example only causes problems when the implicit instantiation is requested \*above\* the definition. And that's also a prerequisite for the quirky AST. Compare: https://godbolt.org/z/4eT8Er3ev

So I think explicit specializations are actually fine because it's an error to perform them after an implicit instantiation: https://godbolt.org/z/ddT4bffvK

https://github.com/llvm/llvm-project/pull/168954