mapper: reconcile self on policy recomputes

Self renders from the same state as peers, so leaving it out of policy
responses hid an exit node's approved routes until it reconnected.

Fixes #3502

integration/route_test.go

@@ -1693,6 +1693,11 @@ func TestEnablingExitRoutes(t *testing.T) {
 					assert.Contains(c, peerStatus.AllowedIPs.AsSlice(), tsaddr.AllIPv6())
 				}
 			}
+
+			// The approved node must learn its own routes on its live
+			// session, not only after reconnecting (issue #3502).
+			assert.True(c, status.Self.ExitNodeOption,
+				"%s should offer itself as exit node", client.Hostname())
 		}
 	}, integrationutil.ScaledTimeout(10*time.Second), integrationutil.SlowPoll, "clients should see new routes")
 }