Change mp_obj_type_t.name from const char * to qstr.

Ultimately all static strings should be qstr.  This entry in the type
structure is only used for printing error messages (to tell the type of
the bad argument), and printing objects that don't supply a .print method.

py/objset.c

@@ -73,7 +73,7 @@ STATIC mp_obj_t set_make_new(mp_obj_t type_in, uint n_args, uint n_kw, const mp_
 
 const mp_obj_type_t set_it_type = {
     { &mp_const_type },
-    "set_iterator",
+    .name = MP_QSTR_iterator,
     .iternext = set_it_iternext,
 };
 
@@ -447,7 +447,7 @@ STATIC const mp_method_t set_type_methods[] = {
 
 const mp_obj_type_t set_type = {
     { &mp_const_type },
-    "set",
+    .name = MP_QSTR_set,
     .print = set_print,
     .make_new = set_make_new,
     .binary_op = set_binary_op,