[clang] [Clang] Fix a wrong diagnostic about a local variable inside a lambda in unevaluated context need capture (PR #165098)

[Zhikai Zeng via cfe-commits]

Backl1ght wrote:

@Fznamznon @ojhunt Now the patch contains no ternary operator inside an if, and will never pass null to cast.

https://github.com/llvm/llvm-project/pull/165098