fate: add rawdiff and use it for subtitles

We want subtitles tests to match exactly line endings and trailing
characters.

tests/fate-run.sh

@@ -229,6 +229,7 @@ fi
 if test -e "$ref" || test $cmp = "oneline" ; then
     case $cmp in
         diff)   diff -u -b "$ref" "$outfile"            >$cmpfile ;;
+        rawdiff)diff -u    "$ref" "$outfile"            >$cmpfile ;;
         oneoff) oneoff     "$ref" "$outfile"            >$cmpfile ;;
         stddev) stddev     "$ref" "$outfile"            >$cmpfile ;;
         oneline)oneline    "$ref" "$outfile"            >$cmpfile ;;

tests/fate/subtitles.mak

@@ -62,4 +62,5 @@ FATE_SUBTITLES-$(call ENCMUX, ASS, ASS) += $(FATE_SUBTITLES_ASS-yes)
 FATE_SUBTITLES += $(FATE_SUBTITLES-yes)
 
 FATE_SAMPLES_FFMPEG += $(FATE_SUBTITLES)
+fate-subtitles: CMP = rawdiff
 fate-subtitles: $(FATE_SUBTITLES)