Implement RMStream stream-specific private data object in the RM demuxer.

This allows multiple video or audio streams per .rm file. See mailinglist
thread "[PATCH] rmdec.c: implement RMVideo/AudioStream".

Originally committed as revision 16365 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/rm.h

@@ -24,6 +24,11 @@
 
 #include "avformat.h"
 
+typedef struct RMStream RMStream;
+
+RMStream *ff_rm_alloc_rmstream (void);
+void      ff_rm_free_rmstream  (RMStream *rms);
+
 /*< input format for Realmedia-style RTSP streams */
 extern AVInputFormat rdt_demuxer;