FS-11721 add a send queue to buffer msg messages before msrp socket is ready

src/include/switch_msrp.h

@@ -118,6 +118,7 @@ struct switch_msrp_session_s{
 	uint8_t frame_data[SWITCH_RTP_MAX_BUF_LEN];
 	int running;
 	void *user_data;
+	switch_queue_t *send_queue;
 };
 
 SWITCH_DECLARE(switch_status_t) switch_msrp_init(void);