Move rm_codec_tags to rm.c so muxer/demuxer can share it.

Patch by Francesco Lavra <francescolavra interfree it>.

Originally committed as revision 23360 to svn://svn.ffmpeg.org/ffmpeg/trunk
diff --git a/libavformat/rm.h b/libavformat/rm.h
index 4e63114..182fddf 100644
--- a/libavformat/rm.h
+++ b/libavformat/rm.h
@@ -23,9 +23,11 @@
 #define AVFORMAT_RM_H
 
 #include "avformat.h"
+#include "internal.h"
 
 extern const char * const ff_rm_metadata[4];
 extern const unsigned char ff_sipr_subpk_size[4];
+extern const AVCodecTag ff_rm_codec_tags[];
 
 typedef struct RMStream RMStream;