[clang] Control analysis-based diagnostics with #pragma (PR #136323)

[Nikita Popov via cfe-commits]

nikic wrote:

FYI this introduces some overhead: https://llvm-compile-time-tracker.com/compare.php?from=2a9f77f6bd48d757b2d45aadcb6cf76ef4b4ef32&to=71ce9e26aec00e4af27a69ccfab8ca1773ed7018&stat=instructions:u About 0.3% on clang files.

https://github.com/llvm/llvm-project/pull/136323