avcodec/utils: Use 64bit for aspect ratio calculation in avcodec_string()

Fixes integer overflow
Fixes: 3a45b2ae02f2cf12b7bd99543cdcdae5/asan_heap-oob_1dff502_8022_899f75e1e81046ebd7b6c2394a1419f4.mov

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/utils.c

@@ -2760,8 +2760,8 @@ void avcodec_string(char *buf, int buf_size, AVCodecContext *enc, int encode)
 
             if (enc->sample_aspect_ratio.num) {
                 av_reduce(&display_aspect_ratio.num, &display_aspect_ratio.den,
-                          enc->width * enc->sample_aspect_ratio.num,
-                          enc->height * enc->sample_aspect_ratio.den,
+                          enc->width * (int64_t)enc->sample_aspect_ratio.num,
+                          enc->height * (int64_t)enc->sample_aspect_ratio.den,
                           1024 * 1024);
                 snprintf(buf + strlen(buf), buf_size - strlen(buf),
                          " [SAR %d:%d DAR %d:%d]",