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/google.golang.org/appengine/internal/main_vm.go

@@ -0,0 +1,48 @@
+// Copyright 2011 Google Inc. All rights reserved.
+// Use of this source code is governed by the Apache 2.0
+// license that can be found in the LICENSE file.
+
+// +build !appengine
+
+package internal
+
+import (
+	"io"
+	"log"
+	"net/http"
+	"net/url"
+	"os"
+)
+
+func Main() {
+	installHealthChecker(http.DefaultServeMux)
+
+	port := "8080"
+	if s := os.Getenv("PORT"); s != "" {
+		port = s
+	}
+
+	host := ""
+	if IsDevAppServer() {
+		host = "127.0.0.1"
+	}
+	if err := http.ListenAndServe(host+":"+port, http.HandlerFunc(handleHTTP)); err != nil {
+		log.Fatalf("http.ListenAndServe: %v", err)
+	}
+}
+
+func installHealthChecker(mux *http.ServeMux) {
+	// If no health check handler has been installed by this point, add a trivial one.
+	const healthPath = "/_ah/health"
+	hreq := &http.Request{
+		Method: "GET",
+		URL: &url.URL{
+			Path: healthPath,
+		},
+	}
+	if _, pat := mux.Handler(hreq); pat != healthPath {
+		mux.HandleFunc(healthPath, func(w http.ResponseWriter, r *http.Request) {
+			io.WriteString(w, "ok")
+		})
+	}
+}