avcodec/put_bits: Assert that size in set_put_bits_buffer_size() does not cause integer overflows

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

libavcodec/put_bits.h

@@ -252,6 +252,7 @@ static inline void skip_put_bits(PutBitContext *s, int n)
  */
 static inline void set_put_bits_buffer_size(PutBitContext *s, int size)
 {
+    av_assert0(size <= INT_MAX/8 - 32);
     s->buf_end = s->buf + size;
     s->size_in_bits = 8*size;
 }