Merge pull request #7110 from cgundogan/pr/native_fallthrough

native: add break to satisfy compiler gcc-7.1.1

cpu/native/startup.c

@@ -290,6 +290,7 @@ __attribute__((constructor)) static void startup(int argc, char **argv, char **e
             case 0:
             case 'h':
                 usage_exit(EXIT_SUCCESS);
+                break;
             case 'i':
                 _native_id = atol(optarg);
                 break;