Add rc-sstat script

The rc-sstat script is written to display status of s6 services and
run rc-status to display all services status.

This currently only works on Linux.

scripts/Makefile

@@ -1,5 +1,19 @@
+MK=	../mk
+include ${MK}/os.mk
+
 DIR=	${LIBEXECDIR}/bin
 BIN=	on_ac_power
+INSTALLAFTER = _installafter
+
+ifeq (${OS},Linux)
+SRCS+= rc-sstat.in
+BIN+=	rc-sstat
+endif
+
+_installafter:
+ifeq (${OS},Linux)
+	${INSTALL} -d ${DESTDIR}${SBINDIR}
+	ln -s ${DIR}/rc-sstat ${DESTDIR}/${SBINDIR}/rc-sstat
+endif
 
-MK=	../mk
 include ${MK}/scripts.mk