gluon-mesh-vpn-core: don't consider tunneldigger when fastd is installed

None of our scripts can handle fastd and tunneldigger running at the same
time. When both are installed, ignore tunneldigger.

(cherry picked from commit f6df3b05)

package/gluon-mesh-vpn-core/luasrc/lib/gluon/upgrade/500-mesh-vpn

@@ -52,7 +52,7 @@ uci:save('firewall')
 local has_fastd = unistd.access('/lib/gluon/mesh-vpn/fastd')
 local fastd_enabled = uci:get('fastd', 'mesh_vpn', 'enabled')
 
-local has_tunneldigger = unistd.access('/lib/gluon/mesh-vpn/tunneldigger')
+local has_tunneldigger = (not has_fastd) and unistd.access('/lib/gluon/mesh-vpn/tunneldigger')
 local tunneldigger_enabled = uci:get('tunneldigger', 'mesh_vpn', 'enabled')
 
 local enabled