cmd/cli: add support for no default route systems

Currently, ctrld requires the default route interface existed to be
functional correctly.

However, on systems where default route is non existed, or point to a
virtual interface (like ipsec based VPN), the fact that the OS is using
this interface as default gateway and doesn't actually send things to
127.0.0.1 is not ctrld's problem.

In this case, ctrld should just start normally, without worrying about
the no default route interface problem.

cmd/cli/os_linux.go

@@ -110,8 +110,8 @@ systemdResolve:
 			}
 			time.Sleep(time.Second)
 		}
+		mainLog.Load().Debug().Msg("DNS was not set for some reason")
 	}
-	mainLog.Load().Debug().Msg("DNS was not set for some reason")
 	return nil
 }