80-make-initfs: fix the silliest mistake ever

*Of course* the "weird" [ ... ] || ... construct meant to avoid
the non-zero exit status of the whole thing wasn't employed
where it actually does make the difference!

Thanks ildar@ for hitting and reporting this, as in

  + verbose '/usr/lib64/propagator exists'
  + '[' -n '' ']'
  mki-scripts: .../stage1/scripts.d/80-make-initfs: unable to run script.
  make[3]: *** [run-scripts] Error 1

features.in/stage2/stage1/scripts.d/80-make-initfs

@@ -1,7 +1,7 @@
 #!/bin/sh -efux
 # NB: /etc/initrd.mk carefully prepared by earlier scripts
 
-verbose() { [ -n "$GLOBAL_VERBOSE" ] && echo "** 80-make-initfs: $@" >&2; }
+verbose() { [ -z "$GLOBAL_VERBOSE" ] || echo "** 80-make-initfs: $@" >&2; }
 
 kver="$(rpm -qa 'kernel-image*' \
 	    --qf '%{installtime} %{version}-%{name}-%{release}\n' \