watch: remove unreachable code

Signed-off-by: Sami Kerola <kerolasa@iki.fi>

watch.c

@@ -707,7 +707,5 @@ int main(int argc, char *argv[])
 			usleep(interval * 1000000);
 	}
 
-	endwin();
-
-	return EXIT_SUCCESS;
+	return EXIT_FAILURE;
 }