fate/ffmpeg: Set max_delay for shortest-sub

The aim of this test is to show the interleavement
of the file generated in the first pass; so make the
interleavement queue in the framecrc muxer in the second
pass as small as possible so that the framecrc muxer does not
fix wrong interleavement of the input file behind our backs.

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

tests/fate/ffmpeg.mak

@@ -105,7 +105,7 @@ FATE_SAMPLES_FFMPEG-$(call ALLYES, COLOR_FILTER, VOBSUB_DEMUXER, MATROSKA_DEMUXE
 fate-shortest-sub: CMD = transcode                                                                    \
         vobsub $(TARGET_SAMPLES)/sub/vobsub.idx matroska                                              \
         "-filter_complex 'color=s=1x1:rate=1:duration=400' -pix_fmt rgb24 -allow_raw_vfw 1 -c:s copy -c:v rawvideo"  \
-        "-map 0 -c copy -shortest -shortest_buf_duration 40"
+        "-map 0 -c copy -shortest -shortest_buf_duration 40 -max_delay 1"
 
 # Basic test for fix_sub_duration, which calculates duration based on the
 # following subtitle's pts.