Use Go1.11 module (#5743)

* Migrate to go modules

* make vendor

* Update mvdan.cc/xurls

* make vendor

* Update code.gitea.io/git

* make fmt-check

* Update github.com/go-sql-driver/mysql

* make vendor

vendor/golang.org/x/crypto/ssh/streamlocal.go

@@ -32,6 +32,7 @@ type streamLocalChannelForwardMsg struct {
 
 // ListenUnix is similar to ListenTCP but uses a Unix domain socket.
 func (c *Client) ListenUnix(socketPath string) (net.Listener, error) {
+	c.handleForwardsOnce.Do(c.handleForwards)
 	m := streamLocalChannelForwardMsg{
 		socketPath,
 	}