Split bitstream.h, put the bitstream writer stuff in the new file
put_bits.h.

Originally committed as revision 18461 to svn://svn.ffmpeg.org/ffmpeg/trunk
diff --git a/libavcodec/bitstream.c b/libavcodec/bitstream.c
index 4851098..39dbe04 100644
--- a/libavcodec/bitstream.c
+++ b/libavcodec/bitstream.c
@@ -29,6 +29,7 @@
 
 #include "avcodec.h"
 #include "bitstream.h"
+#include "put_bits.h"
 
 const uint8_t ff_log2_run[32]={
  0, 0, 0, 0, 1, 1, 1, 1,