Added LLVM_FALLTHROUGH to address warning: this statement may fall through. NFC.

llvm-svn: 304473

clang/lib/Parse/ParseDeclCXX.cpp

@@ -4215,6 +4215,7 @@ void Parser::ParseMicrosoftIfExistsClassDeclaration(DeclSpec::TST TagType,
     Diag(Result.KeywordLoc, diag::warn_microsoft_dependent_exists)
       << Result.IsIfExists;
     // Fall through to skip.
+    LLVM_FALLTHROUGH;
       
   case IEB_Skip:
     Braces.skipToEnd();