ike: reuse the reqid of an installed trap having the same config

When we have a trap installed, but a CHILD_SA gets established for the same
config from the peer, we should reuse the same reqid. Otherwise we would have
two identical policies using different reqids, what we can't handle in our
kernel backend.

src/libcharon/sa/child_sa.c

@@ -1149,7 +1149,11 @@ child_sa_t * child_sa_create(host_t *me, host_t* other,
 		}
 		else
 		{
-			this->reqid = ref_get(&reqid);
+			this->reqid = charon->traps->find_reqid(charon->traps, config);
+			if (!this->reqid)
+			{
+				this->reqid = ref_get(&reqid);
+			}
 		}
 	}