mxrouterctl: Fix startup: Don't move lo

Make the code, which moves/creates interface in 'start' the same as the
code in 'restart'. Most importantly this avoids `mxrouterctl start` to
attempt to move 'lo' into the new namespaces.

    root@jabberwocky:/etc/local/mxrouter# mxrouterctl start
    ip netns add MXR
    ip link set lo netns MXR
    RTNETLINK answers: Invalid argument
    previous command failed with exit status 2

Fixes da35f49 ("mxrouterctl: Handle interface changes on reload")

mxrouter/mxrouterctl

@@ -808,13 +808,17 @@ if (!$opt_this_ns) {
 
 		have_netns($NETNS) and die "already running (network namespace $NETNS already exists)\n";
 		create_netns($NETNS);
-		for my $dev (sort keys %$want_if) {
-			move_dev_into_ns($dev,$NETNS);
-		}
 		for my $dev (sort keys %$want_veth) {
+			-d "/sys/class/net/$dev" and next;
 			sys('ip', 'link', 'add', $dev, 'type', 'veth', 'peer', 'name', $dev, 'netns', $NETNS);
 			sys('ip', 'link', 'set', $dev, 'up');
 		}
+		# move interfaces which are still in the init namespace
+		# ignore veth devices and lo, which exists in both namespaces
+		for my $dev (sort keys %$want_if) {
+			$dev eq 'lo'  || $want_veth->{$dev} and next;
+			-d "/sys/class/net/$dev" and sys('ip', 'link', 'set', $dev, 'netns', $NETNS);
+		}
 		system('ip','netns','exec',$NETNS,$0,'--this-ns',@SAVED_ARGV) and exit 1;
 	} elsif ($cmd eq 'stop') {
 		have_netns($NETNS) or die "not running (network namespace $NETNS does not exist)\n";