[clang] [clang][Lex] Fix crash on pragma annotations in preprocessor expressions (PR #232413)

[Ambrose Leeb via cfe-commits]

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

This should come w/ a release note, else this lgtm; I don’t think we can get a `raw_identifier` here, which is the other case in which `getIdentifierInfo()` may assert.

https://github.com/llvm/llvm-project/pull/232413