send signal to all processes in the process group of exec

kill these processes too, they are using the same stdio with
exec, causing pae will not been sent out.

Signed-off-by: Gao feng <omarapazanadi@gmail.com>

Author: gao-feng

src/init.c

@@ -682,7 +682,7 @@ static int hyper_signal_process(struct hyper_pod *pod, char *json, int length)
 		goto out;
 	}
 
-	kill(exec->pid, (int)json_object_get_number(json_object(value), "signal"));
+	kill(-exec->pid, (int)json_object_get_number(json_object(value), "signal"));
 	ret = 0;
 out:
 	json_value_free(value);