[clang-tools-extra] [clang-tidy] Fix modernize-use-noexcept crash on unparsed exception specs (PR #218256)

[Zeyi Xu via cfe-commits]

https://github.com/zeyi2 approved this pull request.

LGTM!

(I'll merge this PR after CI passes, thanks for contribution)

https://github.com/llvm/llvm-project/pull/218256