Add missing 'return on failure'. Previously we'd crash after emitting
the diagnostic.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127480 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/TableGen/TGParser.cpp b/utils/TableGen/TGParser.cpp
index f6041be..59097f9 100644
--- a/utils/TableGen/TGParser.cpp
+++ b/utils/TableGen/TGParser.cpp
@@ -1153,6 +1153,7 @@
         s << "Type mismatch for list, expected list type, got "
           << ItemType->getAsString();
         TokError(s.str());
+        return 0;
       }
       GivenListTy = ListType;
     }