configure: Consolidate rtsp/sdp deps to use _select

This makes e.g. --disable-everything --enable-demuxer=rtsp actually
enable the rtsp demuxer and everything else that is needed.

Originally committed as revision 25356 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -1360,12 +1360,9 @@ mpegtsraw_demuxer_select="mpegts_demuxer"
 mxf_d10_muxer_select="mxf_muxer"
 ogg_demuxer_select="golomb"
 psp_muxer_select="mov_muxer"
-rtsp_demuxer_deps="sdp_demuxer"
-rtsp_demuxer_select="http_protocol"
-rtsp_muxer_deps="sdp_demuxer"
-rtsp_muxer_select="rtp_muxer http_protocol"
-sdp_demuxer_deps="rtp_protocol mpegts_demuxer"
-sdp_demuxer_select="asf_demuxer rm_demuxer"
+rtsp_demuxer_select="http_protocol sdp_demuxer"
+rtsp_muxer_select="rtp_muxer http_protocol sdp_demuxer"
+sdp_demuxer_select="asf_demuxer rm_demuxer rtp_protocol mpegts_demuxer"
 spdif_muxer_select="aac_parser"
 tg2_muxer_select="mov_muxer"
 tgp_muxer_select="mov_muxer"