res_pjsip_sdp_rtp: Fix return code from apply_negotiated_sdp_stream

apply_negotiated_sdp_stream was returning a "1" when no joint
capabilities were found on an outgoing call instead of a "-1".
This indicated to res_pjsip_session that the handler DID handle
the sdp when in fact it didn't.  Without the appropriate setup,
a subsequent media frame coming in would have an invalid stream_num
and cause a seg fault when the stream was attempted to be retrieved.

apply_negotiated_sdp_stream now returns the correct "-1" and any
media is now discarded before it reaches the core stream processing.

ASTERISK-28260
Reported by: Sotiris Ganouris

Change-Id: Ia095cb16b4862f2f6ad6d2d2a77453fa2542371f

res/res_pjsip_sdp_rtp.c

@@ -1941,7 +1941,7 @@ static int apply_negotiated_sdp_stream(struct ast_sip_session *session,
 	}
 
 	if (set_caps(session, session_media, session_media_transport, remote_stream, 0, asterisk_stream)) {
-		return 1;
+		return -1;
 	}
 
 	/* Set the channel uniqueid on the RTP instance now that it is becoming active */