py/objset: Use mp_check_self() to check args of set/frozenset methods.

Following how other objects work, set/frozenset methods should use the
mp_check_self() macro to check the type of the self argument, because in
most cases this check can be a null operation.

Saves about 100-180 bytes of code for builds with set and frozenset
enabled.

py/objset.c

@@ -57,27 +57,21 @@ STATIC bool is_set_or_frozenset(mp_obj_t o) {
     ;
 }
 
-#if MICROPY_PY_BUILTINS_FROZENSET
-STATIC void check_set_or_frozenset(mp_obj_t o) {
-    if (!is_set_or_frozenset(o)) {
-        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "'set' object required"));
-    }
-}
-#else
-#define check_set_or_frozenset(o) check_set(o)
-#endif
+// This macro is shorthand for mp_check_self to verify the argument is a
+// set or frozenset for methods that operate on both of these types.
+#define check_set_or_frozenset(o) mp_check_self(is_set_or_frozenset(o))
 
+// This function is used to verify the argument for methods that modify
+// the set object, and raises an exception if the arg is a frozenset.
 STATIC void check_set(mp_obj_t o) {
-    if (!MP_OBJ_IS_TYPE(o, &mp_type_set)) {
-        // Emulate CPython behavior
+    #if MICROPY_PY_BUILTINS_FROZENSET
+    if (MP_OBJ_IS_TYPE(o, &mp_type_frozenset)) {
+        // Mutable method called on frozenset; emulate CPython behavior, eg:
         // AttributeError: 'frozenset' object has no attribute 'add'
-        #if MICROPY_PY_BUILTINS_FROZENSET
-        if (MP_OBJ_IS_TYPE(o, &mp_type_frozenset)) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_AttributeError, "'frozenset' has no such attribute"));
-        }
-        #endif
-        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "'set' object required"));
+        nlr_raise(mp_obj_new_exception_msg(&mp_type_AttributeError, "'frozenset' has no such attribute"));
     }
+    #endif
+    mp_check_self(MP_OBJ_IS_TYPE(o, &mp_type_set));
 }
 
 STATIC void set_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {