avcodec/flicvideo: Check remaining bytes in FLI*COPY

Fixes: Timeout
Fixes: 37795/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_FLIC_fuzzer-4846536543043584

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpegSigned-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/flicvideo.c

@@ -735,6 +735,8 @@ static int flic_decode_frame_15_16BPP(AVCodecContext *avctx,
                 bytestream2_skip(&g2, chunk_size - 6);
             } else {
 
+                if (bytestream2_get_bytes_left(&g2) < 2 * s->avctx->width * s->avctx->height )
+                    return AVERROR_INVALIDDATA;
                 for (y_ptr = 0; y_ptr < s->frame->linesize[0] * s->avctx->height;
                      y_ptr += s->frame->linesize[0]) {