wgengine: properly clean up freebsd routes and interfaces on close

Signed-off-by: wardn <wardn@users.noreply.github.com>

wgengine/userspace.go

@@ -564,6 +564,7 @@ func (e *userspaceEngine) Close() {
 	e.wgdev.IpcSetOperation(r)
 	e.linkMon.Close()
 	e.router.Close()
+	e.wgdev.Close()
 	e.magicConn.Close()
 	close(e.waitCh)
 }