Fix a crash-on-invalid when parsing a reference to an invalid auto declaration

  auto x((unknown));
  int& y = x;

would crash because we were not flagging 'x' as an invalid declaration here.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@165675 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Parse/ParseDecl.cpp b/lib/Parse/ParseDecl.cpp
index 52bd416..3ef4f38 100644
--- a/lib/Parse/ParseDecl.cpp
+++ b/lib/Parse/ParseDecl.cpp
@@ -1680,6 +1680,7 @@
     }
 
     if (ParseExpressionList(Exprs, CommaLocs)) {
+      Actions.ActOnInitializerError(ThisDecl);
       SkipUntil(tok::r_paren);
 
       if (getLangOpts().CPlusPlus && D.getCXXScopeSpec().isSet()) {