[clang] [clang] Check empty macro name in `#pragma push_macro("")` or `#pragma pop_macro("")` (PR #149982)

[Shafik Yaghmour via cfe-commits]

https://github.com/shafik commented:

Thank you for the fix, please add more details in the summary next time. Something along the lines of "added diagnostic which now triggers when.... which avoids the crash ...."

https://github.com/llvm/llvm-project/pull/149982