avfilter/vf_fade: fix start/duration max value

A fade out (usually at the end of a video) can easily start beyond
INT32_MAX (about 36 minutes).  Regression since d40dc641.

libavfilter/vf_fade.c

@@ -386,13 +386,13 @@ static const AVOption fade_options[] = {
                                                     OFFSET(nb_frames),   AV_OPT_TYPE_INT, { .i64 = 25 }, 0, INT_MAX, FLAGS },
     { "alpha",       "fade alpha if it is available on the input", OFFSET(alpha),       AV_OPT_TYPE_BOOL, {.i64 = 0    }, 0,       1, FLAGS },
     { "start_time",  "Number of seconds of the beginning of the effect.",
-                                                    OFFSET(start_time),  AV_OPT_TYPE_DURATION, {.i64 = 0. }, 0, INT32_MAX, FLAGS },
+                                                    OFFSET(start_time),  AV_OPT_TYPE_DURATION, {.i64 = 0. }, 0, INT64_MAX, FLAGS },
     { "st",          "Number of seconds of the beginning of the effect.",
-                                                    OFFSET(start_time),  AV_OPT_TYPE_DURATION, {.i64 = 0. }, 0, INT32_MAX, FLAGS },
+                                                    OFFSET(start_time),  AV_OPT_TYPE_DURATION, {.i64 = 0. }, 0, INT64_MAX, FLAGS },
     { "duration",    "Duration of the effect in seconds.",
-                                                    OFFSET(duration),    AV_OPT_TYPE_DURATION, {.i64 = 0. }, 0, INT32_MAX, FLAGS },
+                                                    OFFSET(duration),    AV_OPT_TYPE_DURATION, {.i64 = 0. }, 0, INT64_MAX, FLAGS },
     { "d",           "Duration of the effect in seconds.",
-                                                    OFFSET(duration),    AV_OPT_TYPE_DURATION, {.i64 = 0. }, 0, INT32_MAX, FLAGS },
+                                                    OFFSET(duration),    AV_OPT_TYPE_DURATION, {.i64 = 0. }, 0, INT64_MAX, FLAGS },
     { "color",       "set color",                   OFFSET(color_rgba),  AV_OPT_TYPE_COLOR,    {.str = "black"}, CHAR_MIN, CHAR_MAX, FLAGS },
     { "c",           "set color",                   OFFSET(color_rgba),  AV_OPT_TYPE_COLOR,    {.str = "black"}, CHAR_MIN, CHAR_MAX, FLAGS },
     { NULL }