avcodec/dxv: Check remaining space in CHECKPOINT()

Fixes: Timeout (77sec -> 1sec)
Fixes: 13407/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_DXV_fuzzer-5093143018471424

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

libavcodec/dxv.c

@@ -256,6 +256,8 @@ static int decompress_texture_thread(AVCodecContext *avctx, void *arg,
 #define CHECKPOINT(x)                                                         \
     do {                                                                      \
         if (state == 0) {                                                     \
+            if (bytestream2_get_bytes_left(gbc) < 4)                          \
+                return AVERROR_INVALIDDATA;                                   \
             value = bytestream2_get_le32(gbc);                                \
             state = 16;                                                       \
         }                                                                     \