allow committing transaction without a lock file

This is useful to allow front-ends to manage the lock file themselves,
allowing them to ensure database consistency across multiple commands, e.g.:

 paclock --lock
 pacinstall --no-lock foo
 # foo is guaranteed to be installed until the db is unlocked
 paclock --unlock

Signed-off-by: Andrew Gregory <andrew.gregory.8@gmail.com>

lib/libalpm/trans.c

@@ -177,8 +177,6 @@ int SYMEXPORT alpm_trans_commit(alpm_handle_t *handle, alpm_list_t **data)
 	ASSERT(trans != NULL, RET_ERR(handle, ALPM_ERR_TRANS_NULL, -1));
 	ASSERT(trans->state == STATE_PREPARED, RET_ERR(handle, ALPM_ERR_TRANS_NOT_PREPARED, -1));
 
-	ASSERT(!(trans->flags & ALPM_TRANS_FLAG_NOLOCK), RET_ERR(handle, ALPM_ERR_TRANS_NOT_LOCKED, -1));
-
 	/* If there's nothing to do, return without complaining */
 	if(trans->add == NULL && trans->remove == NULL) {
 		return 0;