[clang] [clang][Lex] Don't parsing header name as a string literal (PR #201763)

[Yihan Wang via cfe-commits]

yronglin wrote:

> Thank you for the fix! Please make sure your summaries briefly explain the problem, your approach to solving it and any other details that stand out.

Thanks for the review! I updated the summaries.

https://github.com/llvm/llvm-project/pull/201763