Fix DictNode nogil attribute lookup

Cython/Compiler/ExprNodes.py

@@ -8833,7 +8833,7 @@ class DictNode(ExprNode):
                     code.putln('}')
                 if self.exclude_null_values:
                     code.putln('}')
-            elif self.type.nogil:
+            elif hasattr(self.type, 'nogil') and self.type.nogil:
                 code.putln("%s->%s = %s;" % (
                         self.result(),
                         item.key.value,