Update dict clear error kind

Author: vsakkas

mypyc/primitives/dict_ops.py

@@ -148,7 +148,7 @@
     arg_types=[dict_rprimitive],
     return_type=void_rtype,
     c_function_name='CPyDict_Clear',
-    error_kind=ERR_NEVER)
+    error_kind=ERR_MAGIC)
 
 # list(dict.keys())
 dict_keys_op = custom_op(

mypyc/test-data/run-dicts.test

@@ -92,6 +92,7 @@ assert get_content(od) == ([3, 1], [4, 2], [(3, 4), (1, 2)])
 assert get_content_set({1: 2}) == ({1}, {2}, {(1, 2)})
 assert get_content_set(od) == ({1, 3}, {2, 4}, {(1, 2), (3, 4)})
 
+from collections import defaultdict
 d = {'a': 1, 'b': 2}
 d.clear()
 assert d == {}