golomb: Fix overread in get_ur_golomb_jpegls()

Fixes Ticket600
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/golomb.h

@@ -302,6 +302,8 @@ static inline int get_ur_golomb_jpegls(GetBitContext *gb, int k, int limit, int
     }else{
         int i;
         for(i=0; SHOW_UBITS(re, gb, 1) == 0; i++){
+            if (get_bits_left(gb)<=0)
+                return -1;
             LAST_SKIP_BITS(re, gb, 1);
             UPDATE_CACHE(re, gb);
         }