Add support for ffmpeg's demuxer-specific options.

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@36452 b3059339-0415-0410-9bf9-f77b7e298cf2
Add support for -rtsp-stream-over-tcp and -rtsp-stream-over-http for FFmpeg.

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@36453 b3059339-0415-0410-9bf9-f77b7e298cf2
Autodetect if pthread_cancel is available.

Necessary for properly working reception of streams
via UDP, e.g. via FFmpeg's RTSP-over-UDP implementation.

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@36454 b3059339-0415-0410-9bf9-f77b7e298cf2
Move rtsp_transport_* variables to demuxer.c

Also make the corresponding command-line options always
available.
Most users will have some kind of rtsp support, possibly
through ffmpeg.
Putting it under CONFIG_NETWORKING would be more correct,
but doesn't seem worth the effort to me.

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@36455 b3059339-0415-0410-9bf9-f77b7e298cf2