Remove "single" runlevel directory

Single user mode should be handled in the init process directly.

runlevels/Makefile

@@ -13,7 +13,6 @@ BOOTDIR=	${LEVELDIR}/boot
 DEFAULTDIR=	${LEVELDIR}/default
 NONETWORKDIR=	${LEVELDIR}/nonetwork
 SHUTDOWNDIR=	${LEVELDIR}/shutdown
-SINGLEDIR=	${LEVELDIR}/single
 
 ifeq (${MKNET},yes)
 BOOT+= network staticroute
@@ -91,9 +90,6 @@ install:
 			fi; \
 			ln -snf ${INITDIR}/"$$x" ${SHUTDOWNDIR}/"$$x" || exit $$?; done \
 	fi
-	if ! test -d "${SINGLEDIR}"; then \
-		${INSTALL} -d ${SINGLEDIR} || exit $$?; \
-	fi
 	if test "${MKSYSVINIT}" = yes && test "${OS}" = Linux; then \
 		for x in tty1 tty2 tty3 tty4 tty5 tty6; do \
 			ln -snf ${INITDIR}/agetty ${DESTDIR}/${INITDIR}/"agetty.$$x" || exit $$?; \
@@ -101,7 +97,6 @@ install:
 		for x in tty1 tty2 tty3 tty4 tty5 tty6; do \
 			ln -snf ${INITDIR}/agetty.$$x ${DEFAULTDIR}/"agetty.$$x" || exit $$?; \
 		done; \
-		ln -snf ${INITDIR}/agetty.tty1 ${SINGLEDIR}/agetty.tty1 || exit $$?; \
 	fi
 
 check test::