rtp sout: fix reporting of sequence number when using SRTP

(cherry picked from commit 0b01c67ef5204d352701f15617b69859f4dcfaa0)
Signed-off-by: Pierre Ynard <linkfanel@yahoo.fr>

modules/stream_out/rtp.c

@@ -954,8 +954,6 @@ static sout_stream_id_t *Add( sout_stream_t *p_stream, es_format_t *p_fmt )
     vlc_rand_bytes (&id->i_sequence, sizeof (id->i_sequence));
     vlc_rand_bytes (id->ssrc, sizeof (id->ssrc));
 
-    id->i_seq_sent_next = id->i_sequence;
-
     id->psz_enc    = NULL;
     id->psz_fmtp   = NULL;
     id->i_clock_rate = 90000; /* most common case for video */
@@ -1022,6 +1020,8 @@ static sout_stream_id_t *Add( sout_stream_t *p_stream, es_format_t *p_fmt )
     }
 #endif
 
+    id->i_seq_sent_next = id->i_sequence;
+
     if( p_sys->psz_destination != NULL )
     {
         int type = SOCK_STREAM;