skip_bits: dont call UPDATE_CACHE

UPDATE_CACHE isnt needed and can cause segfaults
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/get_bits.h

@@ -292,7 +292,6 @@ static inline unsigned int show_bits(GetBitContext *s, int n)
 static inline void skip_bits(GetBitContext *s, int n)
 {
     OPEN_READER(re, s);
-    UPDATE_CACHE(re, s);
     LAST_SKIP_BITS(re, s, n);
     CLOSE_READER(re, s);
 }