pkg: install via `install', and fix unknown version hiccup

Makefile

@@ -8,6 +8,8 @@ umount:
 
 install:
 	@mkdir -p ${DESTDIR}/usr/local
+	@cp ${.CURDIR}/pkg/+POST_INSTALL ${DESTDIR}
+	@cp ${.CURDIR}/pkg/+PRE_DEINSTALL ${DESTDIR}
 	@cp -r ${.CURDIR}/src/* ${DESTDIR}/usr/local
 	@(cd ${.CURDIR}/src; find * -type f) | \
 	    xargs -n1 printf "/usr/local/%s\n"

pkg/+POST_INSTALL

@@ -19,6 +19,3 @@ if [ -f /usr/local/etc/rc ]; then /usr/local/etc/rc; exit 0; fi
 EOG
 cat /etc/rc.bak >> /etc/rc
 rm -f /etc/rc.bak
-
-echo "Writing OPNsense version"
-echo "${REPO_VERSION}-${REPO_COMMENT}" > /usr/local/etc/version

pkg/+PRE_DEINSTALL

@@ -14,6 +14,3 @@ rm -f /etc/rc.bak
 
 echo "Enabling FreeBSD mirror"
 sed -i "" -e "s/^  enabled: no$/  enabled: yes/" /etc/pkg/FreeBSD.conf
-
-echo "Removing OPNsense version"
-rm -f /usr/local/etc/version