[clang] [clang-tools-extra] [llvm] [clang] Introduce diagnostics suppression mappings (PR #112517)

[Ilya Biryukov via cfe-commits]

================
@@ -108,6 +108,9 @@ class DiagnosticOptions : public RefCountedBase<DiagnosticOptions>{
   /// The file to serialize diagnostics to (non-appending).
   std::string DiagnosticSerializationFile;
 
+  /// File that defines suppression mappings.
----------------
ilya-biryukov wrote:

NIT: diagnostic suppression mappings?

I can imagine being confused had I not had this context ("what are supressions and why we need to map them?")

https://github.com/llvm/llvm-project/pull/112517