avformat/utils: Use av_realloc_array for reallocating array

Also improve the size check a bit; given that av_realloc_array()
checks for overflow itself, we only have to check for
nb_side_data + 1 still being representable in an int.
But given that we can check for representability in size_t
at no additional cost we do so as it leads to a nicer error code.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavformat/utils.c

@@ -1739,10 +1739,10 @@ int av_stream_add_side_data(AVStream *st, enum AVPacketSideDataType type,
         }
     }
 
-    if ((unsigned)st->nb_side_data + 1 >= INT_MAX / sizeof(*st->side_data))
+    if (st->nb_side_data + 1U > FFMIN(INT_MAX, SIZE_MAX / sizeof(*tmp)))
         return AVERROR(ERANGE);
 
-    tmp = av_realloc(st->side_data, (st->nb_side_data + 1) * sizeof(*tmp));
+    tmp = av_realloc_array(st->side_data, st->nb_side_data + 1, sizeof(*tmp));
     if (!tmp) {
         return AVERROR(ENOMEM);
     }