fate: add an attachment to the Matroska test.

tests/lavf-regression.sh

@@ -137,6 +137,8 @@ do_lavf nut "" "-acodec mp2 -ab 64k"
 fi
 
 if [ -n "$do_mkv" ] ; then
+do_lavf mkv "" "-acodec mp2 -ab 64k -vcodec mpeg4 \
+ -attach ${raw_src%/*}/00.pgm -metadata:s:t mimetype=image/x-portable-greymap"
 do_lavf mkv "" "-acodec mp2 -ab 64k -vcodec mpeg4"
 fi
 

tests/ref/lavf/mkv

@@ -1,3 +1,6 @@
+b53f31e572394f225aff0bc82b5d1cc9 *./tests/data/lavf/lavf.mkv
+472553 ./tests/data/lavf/lavf.mkv
+./tests/data/lavf/lavf.mkv CRC=0x4780846b
 84dcb326fe85aeeb5768beb44372f248 *./tests/data/lavf/lavf.mkv
 320297 ./tests/data/lavf/lavf.mkv
 ./tests/data/lavf/lavf.mkv CRC=0x4780846b