[clang] [clang][analyzer] Diagnose dead stores on parenthesized lvalues (PR #227176)

[Donát Nagy via cfe-commits]

https://github.com/NagyDonat approved this pull request.

Looks good to me, very small change, but fixes a real oversight in this checker.

@crisclacerda Should I merge this?

https://github.com/llvm/llvm-project/pull/227176