strongswan: remove synthesized ipsec conf files

If you shutdown ipsec service, and it doesn't clean up
/var/ipsec/ipsec.conf, then when you start swanctl service it
might see an incompatible file on startup.  Remedy is to
remove unneeded files when shutting down the service.  They
can always be regenerated when the service starts again.

Signed-off-by: Philip Prindeville <philipp@redfish-solutions.com>
(cherry picked from commit baa38a1420)

net/strongswan/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=strongswan
 PKG_VERSION:=5.9.1
-PKG_RELEASE:=6
+PKG_RELEASE:=7
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.bz2
 PKG_SOURCE_URL:=https://download.strongswan.org/ https://download2.strongswan.org/

net/strongswan/files/ipsec.init

@@ -331,6 +331,12 @@ reload_service() {
 	start
 }
 
+stop_service() {
+	ipsec_reset
+	swan_reset
+	secret_reset
+}
+
 check_ipsec_interface() {
 	local intf