fate/mov : use do_md5sum for mov-faststart-4gb-overflow test

fix test on osx

based on suggestion by Hendrik Leppkes

tests/fate/mov.mak

@@ -119,7 +119,7 @@ fate-mov-guess-delay-1: CMD = run ffprobe$(PROGSSUF)$(EXESUF) -show_entries stre
 fate-mov-guess-delay-2: CMD = run ffprobe$(PROGSSUF)$(EXESUF) -show_entries stream=has_b_frames -select_streams v $(TARGET_SAMPLES)/h264/h264_3bf_pyramid_nobsrestriction.mp4
 fate-mov-guess-delay-3: CMD = run ffprobe$(PROGSSUF)$(EXESUF) -show_entries stream=has_b_frames -select_streams v $(TARGET_SAMPLES)/h264/h264_4bf_pyramid_nobsrestriction.mp4
 
-fate-mov-faststart-4gb-overflow: CMD = run tools/qt-faststart$(EXESUF) $(TARGET_SAMPLES)/mov/faststart-4gb-overflow.mov faststart-4gb-overflow-output.mov > /dev/null ; md5sum faststart-4gb-overflow-output.mov | cut -d " " -f1 ; rm faststart-4gb-overflow-output.mov
+fate-mov-faststart-4gb-overflow: CMD = run tools/qt-faststart$(EXESUF) $(TARGET_SAMPLES)/mov/faststart-4gb-overflow.mov faststart-4gb-overflow-output.mov > /dev/null ; do_md5sum faststart-4gb-overflow-output.mov | cut -d " " -f1 ; rm faststart-4gb-overflow-output.mov
 fate-mov-faststart-4gb-overflow: CMP = oneline
 fate-mov-faststart-4gb-overflow: REF = bc875921f151871e787c4b4023269b29