Slightly improve my previous commit.

Just comment out the atrun line instead of completely removing it. It is
not a bad idea to leave it as a reference in case someone decides to
install atrun by hand afterwards.

etc/Makefile

@@ -162,7 +162,7 @@ distribution:
 	    ${INSTALL} -o ${BINOWN} -g ${BINGRP} -m 600 \
 		master.passwd nsmb.conf opieaccess ${DESTDIR}/etc;
 .if ${MK_AT} == "no"
-	sed -i "" -e '/atrun/d' ${DESTDIR}/etc/crontab
+	sed -i "" -e 's;.*/usr/libexec/atrun;#&;' ${DESTDIR}/etc/crontab
 .endif
 .if ${MK_TCSH} == "no"
 	sed -i "" -e 's;/bin/csh;/bin/sh;' ${DESTDIR}/etc/master.passwd