review: remove FIXME

- this is correct as we do want to add the newly constructed Declaration
into the current decl context, such that we can retrieve it later when
we look it up from the function declaration in the same context

Author: inbelic

clang/lib/Parse/ParseDeclCXX.cpp

@@ -5279,7 +5279,7 @@ void Parser::ParseMicrosoftRootSignatureAttributeArgs(ParsedAttributes &Attrs) {
 
       // Create the Root Signature
       auto *SignatureDecl = HLSLRootSignatureDecl::Create(
-          Actions.getASTContext(), /*FIXME?*/ Actions.CurContext,
+          Actions.getASTContext(), /*DeclContext=*/Actions.CurContext,
           RootSignatureLoc, DeclIdent, RootElements);
       SignatureDecl->setImplicit();
       Actions.PushOnScopeChains(SignatureDecl, getCurScope());