avcodec/jpegxl_parser: Check for ctx->skip overflow

Fixes: out of array access
Fixes: 62113/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-5025082076168192

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

libavcodec/jpegxl_parser.c

@@ -1326,7 +1326,7 @@ static int skip_boxes(JXLParseContext *ctx, const uint8_t *buf, int buf_size)
         if (!size)
             return AVERROR_INVALIDDATA;
         /* invalid ISOBMFF size */
-        if (size <= head_size + 4)
+        if (size <= head_size + 4 || size > INT_MAX - ctx->skip)
             return AVERROR_INVALIDDATA;
 
         ctx->skip += size;