Do not assume iptables-save is available

mobile/src/main/java/be/mygod/vpnhotspot/TetheringService.kt

@@ -51,7 +51,7 @@ class TetheringService : Service(), VpnMonitor.Callback, IpNeighbourMonitor.Call
                 for ((downstream, value) in routings) if (value == null) {
                     // system tethering already has working forwarding rules
                     // so it doesn't make sense to add additional forwarding rules
-                    val routing = Routing(upstream, downstream).rule().forward(true).dnsRedirect(dns)
+                    val routing = Routing(upstream, downstream).rule().forward().dnsRedirect(dns)
                     if (routing.start()) routings[downstream] = routing else {
                         failed = true
                         routing.stop()

mobile/src/main/java/be/mygod/vpnhotspot/net/Routing.kt

@@ -32,10 +32,10 @@ class Routing(val upstream: String?, val downstream: String, ownerAddress: InetA
 
         fun dump() = loggerSu("""
                 |echo iptables
-                |iptables-save
+                |sh -c 'exec -a iptables-save iptables'
                 |echo
                 |echo iptables -t nat
-                |iptables-save -t nat
+                |sh -c 'exec -a iptables-save iptables -t nat'
                 |echo
                 |echo ip rule
                 |ip rule