strongswan: enable IKEv2 Mediation Extension

Closes #3905.

Signed-off-by: Stijn Tintel <stijn@linux-ipv6.be>

net/strongswan/Makefile

@@ -374,6 +374,7 @@ CONFIGURE_ARGS+= \
 	--disable-scripts \
 	--disable-static \
 	--disable-fast \
+	--enable-mediation \
 	--with-systemdsystemunitdir=no \
 	$(if $(CONFIG_PACKAGE_strongswan-utils),--enable-pki --enable-scepclient,--disable-pki --disable-scepclient) \
 	--with-random-device=/dev/random \