[clang] [analyzer] Fix [[clang::suppress]] for tricky template specializations (PR #178441)

[Ziqing Luo via cfe-commits]

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ziqingluo-90 wrote:

Trying to understand the bug:  what will be `DeclWithIssue` if the bug is not fixed by the end of the loop?  If it is the `TranslationUnitDecl`, it still includes the AST node with the suppression attribute?   
In what circumstances `DeclWithIssue` does not hold the `TranslationUnitDecl` at the loop end?

https://github.com/llvm/llvm-project/pull/178441