monitor: consitify qmp_send_response() QDict argument

Signed-off-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Message-Id: <20180829134043.31706-2-marcandre.lureau@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

monitor.c

@@ -503,9 +503,9 @@ int monitor_fprintf(FILE *stream, const char *fmt, ...)
     return 0;
 }
 
-static void qmp_send_response(Monitor *mon, QDict *rsp)
+static void qmp_send_response(Monitor *mon, const QDict *rsp)
 {
-    QObject *data = QOBJECT(rsp);
+    const QObject *data = QOBJECT(rsp);
     QString *json;
 
     json = mon->flags & MONITOR_USE_PRETTY ? qobject_to_json_pretty(data) :