[clang] [Clang][Sema] Warn when 'exclude_from_explicit_instantiation' attribute is used on local classes and members thereof (PR #88777)

[Krystian Stasiowski via cfe-commits]

================
@@ -9315,6 +9330,9 @@ ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D, const ParsedAttr &AL,
   case ParsedAttr::AT_Error:
     handleErrorAttr(S, D, AL);
     break;
+  case ParsedAttr::AT_ExcludeFromExplicitInstantiation:
----------------
sdkrystian wrote:

`exclude_from_explicit_instantiation` had no 'handle' function prior to this patch -- the only restriction was that it must be applied to the declaration of a variable, function, or class. 

https://github.com/llvm/llvm-project/pull/88777