[clang] Thread Safety Analysis: Support warning on obtaining address of guarded variables (PR #123063)

[Nick Desaulniers via cfe-commits]

nickdesaulniers wrote:

Looks like the kernel patches [use](https://github.com/google/kernel-sanitizers/commit/81883e1fa377d866c288192b6eb8334bcf10f38f) `-fexperimental-late-parse-attributes`? :(

https://github.com/llvm/llvm-project/pull/123063