[clang] [analyzer] Fix use-after-free in CheckerContext::getMacroNameOrSpelling (PR #194174)

[Balázs Benics via cfe-commits]

steakhal wrote:

Offline I've discussed this change with @Xazax-hun and we agreed on not changing the used API - and only focus the patch on fixing the lifetime issue.

https://github.com/llvm/llvm-project/pull/194174