Check we have a list before running depends.

src/librc/librc-depend.c

@@ -566,6 +566,9 @@ RC_STRINGLIST *rc_deptree_order(const RC_DEPTREE *deptree,
 		}
 	}
 
+	if (!list)
+		return NULL;
+
 	/* Now we have our lists, we need to pull in any dependencies
 	   and order them */
 	types = rc_stringlist_new();