avcodec/avs3_parser: assert the return value of init_get_bits()

Fixes: CID1492867 Unchecked return value

Sponsored-by: Sovereign Tech Fund
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit f9218e4d52)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/avs3_parser.c

@@ -73,7 +73,8 @@ static void parse_avs3_nal_units(AVCodecParserContext *s, const uint8_t *buf,
             GetBitContext gb;
             int profile, ratecode, low_delay;
 
-            init_get_bits8(&gb, buf + 4, buf_size - 4);
+            av_unused int ret = init_get_bits(&gb, buf + 4, 100);
+            av_assert1(ret >= 0);
 
             s->key_frame = 1;
             s->pict_type = AV_PICTURE_TYPE_I;