Fix compilatio error by using [[fallthrough]]

Signed-off-by: Jiahao XU <[email protected]>

src/utility.c

@@ -327,6 +327,7 @@ void visit_all_subdirs(const char *path, subdir_visiter visiter, ...)
                 // Check if it is a dir after resolution
                 if (!isdir(path, path_fd, ent->d_name))
                     break;
+                [[fallthrough]];
 
             case DT_DIR:
                 if (strcmp(ent->d_name, ".") != 0 && strcmp(ent->d_name, "..") != 0)