lib-storage: remove attribute accessibility checks

index_storage_attribute_{set,get} should assume that the caller performed
due diligence and checked whether or not the user is allowed to store under
the key.

src/lib-storage/index/index-attribute.c

@@ -197,13 +197,6 @@ int index_storage_attribute_set(struct mailbox_transaction_context *t,
 	time_t ts = value->last_change != 0 ? value->last_change : ioloop_time;
 	int ret = 0;
 
-	if (!t->internal_attribute &&
-	    !MAILBOX_ATTRIBUTE_KEY_IS_USER_ACCESSIBLE(key)) {
-		mail_storage_set_error(t->box->storage, MAIL_ERROR_PARAMS,
-			"Internal attributes cannot be changed directly");
-		return -1;
-	}
-
 	if (index_storage_attribute_get_dict_trans(t, type, &dtrans,
 						   &mailbox_prefix) < 0)
 		return -1;
@@ -238,10 +231,6 @@ int index_storage_attribute_get(struct mailbox_transaction_context *t,
 
 	memset(value_r, 0, sizeof(*value_r));
 
-	if (!t->internal_attribute &&
-	    !MAILBOX_ATTRIBUTE_KEY_IS_USER_ACCESSIBLE(key))
-		return 0;
-
 	if (index_storage_get_dict(t->box, type, &dict, &mailbox_prefix) < 0)
 		return -1;