randomtest fixes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/testsuite/du/du-m-works b/testsuite/du/du-m-works
index 6e733c0..9fa7437 100644
--- a/testsuite/du/du-m-works
+++ b/testsuite/du/du-m-works
@@ -1,6 +1,4 @@
 # FEATURE: CONFIG_FEATURE_HUMAN_READABLE
 
-d=/bin
-du -m "$d" > logfile.gnu
-busybox du -m "$d" > logfile.bb
-cmp logfile.gnu logfile.bb
+dd if=/dev/zero of=file bs=1M count=1 2>/dev/null
+test x"`busybox du -m .`" = x"1	."