Rename put_string to ff_put_string to avoid a symbol clash on Mac OS X.

Originally committed as revision 4597 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/bitstream.c

@@ -37,7 +37,7 @@ void align_put_bits(PutBitContext *s)
 #endif
 }
 
-void put_string(PutBitContext * pbc, char *s, int put_zero)
+void ff_put_string(PutBitContext * pbc, char *s, int put_zero)
 {
     while(*s){
         put_bits(pbc, 8, *s);