sapenc: Declare a dependency on rtp_protocol, too

The SAP muxer uses network functions directly, uses the rtp protocol and the
udp protocol. The network functions and the udp protocol are both transitively
enabled via the rtp protocol, so that's the only dependency that needs to
be stated.

Originally committed as revision 25423 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -1363,8 +1363,7 @@ ogg_demuxer_select="golomb"
 psp_muxer_select="mov_muxer"
 rtsp_demuxer_select="http_protocol sdp_demuxer"
 rtsp_muxer_select="rtp_muxer http_protocol sdp_demuxer"
-sap_muxer_deps="network"
-sap_muxer_select="rtp_muxer"
+sap_muxer_select="rtp_muxer rtp_protocol"
 sdp_demuxer_select="asf_demuxer rm_demuxer rtp_protocol mpegts_demuxer mov_demuxer"
 spdif_muxer_select="aac_parser"
 tg2_muxer_select="mov_muxer"