avformat/tedcaptionsdec: Check for overflow in parse_int()

Fixes: signed integer overflow: 1111111111111111111 * 10 cannot be represented in type 'long'
Fixes: 26892/clusterfuzz-testcase-minimized-ffmpeg_dem_TEDCAPTIONS_fuzzer-5756045055754240

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit b0f8586ca9)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/tedcaptionsdec.c

@@ -181,6 +181,8 @@ static int parse_int(AVIOContext *pb, int *cur_byte, int64_t *result)
     if ((unsigned)*cur_byte - '0' > 9)
         return AVERROR_INVALIDDATA;
     while (BETWEEN(*cur_byte, '0', '9')) {
+        if (val > INT_MAX/10 - (*cur_byte - '0'))
+            return AVERROR_INVALIDDATA;
         val = val * 10 + (*cur_byte - '0');
         next_byte(pb, cur_byte);
     }