[clang] [clang] support Wold-style-declaration (PR #78837)

[Aaron Ballman via cfe-commits]

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@@ -4104,6 +4106,7 @@ void Parser::ParseDeclarationSpecifiers(
         isInvalid = true;
       } else {
         isInvalid = DS.setFunctionSpecVirtual(Loc, PrevSpec, DiagID);
+        isFunctionSpecifier = true;
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AaronBallman wrote:

C doesn't have virtual functions, so no need for this change.

https://github.com/llvm/llvm-project/pull/78837