vorbisdec: Use int instead of uint16_fast_t for index variables

uint16_fast_t is unsigned int (or long) on Linux, which when compared
with int results in an unsigned compare.

Originally committed as revision 24994 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/vorbis_dec.c

@@ -467,7 +467,7 @@ static uint_fast8_t vorbis_floor1_decode(vorbis_context *vc,
 static int vorbis_parse_setup_hdr_floors(vorbis_context *vc)
 {
     GetBitContext *gb = &vc->gb;
-    uint_fast16_t i,j,k;
+    int i,j,k;
 
     vc->floor_count = get_bits(gb, 6) + 1;