Make bitstream_* fields unsigned.

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@14280 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libavcodec/flac.c

@@ -68,8 +68,8 @@ typedef struct FLACContext {
 
     int32_t *decoded[MAX_CHANNELS];
     uint8_t *bitstream;
-    int bitstream_size;
-    int bitstream_index;
+    unsigned int bitstream_size;
+    unsigned int bitstream_index;
     unsigned int allocated_bitstream_size;
 } FLACContext;