[clang] [Clang] Fix crash with `source_location` in lambda declarators. (PR #107411)

[Younan Zhang via cfe-commits]

zyn0217 wrote:

While looking at it, I found another bug where we seem to have problems mangling `std::source_location`
https://clang.godbolt.org/z/467E19h45

https://github.com/llvm/llvm-project/pull/107411