Allow IPComp on NATed connections, both for IKEv1 and IKEv2

While this was problematic in earlier releases, it seems that it works just
fine the way we handle compression now. So there is no need to disable it over
NATed connections or when using forceencaps.

src/libcharon/sa/ikev2/tasks/child_create.c

@@ -678,13 +678,6 @@ static void build_payloads(private_child_create_t *this, message_t *message)
 static void add_ipcomp_notify(private_child_create_t *this,
 								  message_t *message, u_int8_t ipcomp)
 {
-	if (this->ike_sa->has_condition(this->ike_sa, COND_NAT_ANY))
-	{
-		DBG1(DBG_IKE, "IPComp is not supported if either peer is natted, "
-			 "IPComp disabled");
-		return;
-	}
-
 	this->my_cpi = this->child_sa->alloc_cpi(this->child_sa);
 	if (this->my_cpi)
 	{