avcodec/put_bits: Update size_in_bits in set_put_bits_buffer_size()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit e4c2ec879b)

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

libavcodec/put_bits.h

@@ -235,6 +235,7 @@ static inline void skip_put_bits(PutBitContext *s, int n)
 static inline void set_put_bits_buffer_size(PutBitContext *s, int size)
 {
     s->buf_end = s->buf + size;
+    s->size_in_bits = 8*size;
 }
 
 #endif /* AVCODEC_PUT_BITS_H */