[clang] [Clang] handle invalid close location in static assert declaration (PR #108701)

[Shafik Yaghmour via cfe-commits]

shafik wrote:

So this looks like a regression: https://gcc.godbolt.org/z/h6GexT18E

Can we figure out which PR this regression came from and make sure the code change makes sense in light of that PR? 

Also please add a more detailed summary to this PR, describing why the crash happens and the approach the PR takes to fixing it.

https://github.com/llvm/llvm-project/pull/108701