update vendor

Signed-off-by: Jess Frazelle <acidburn@microsoft.com>

vendor/google.golang.org/grpc/go_vet/vet.go

@@ -0,0 +1,47 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// vet.go is a script to check whether files that are supposed to be built on appengine import
+// unsupported package (e.g. "unsafe", "syscall") or not.
+package main
+
+import (
+	"fmt"
+	"go/build"
+	"os"
+)
+
+func main() {
+	b := build.Default
+	b.BuildTags = []string{"appengine", "appenginevm"}
+	argsWithoutProg := os.Args[1:]
+	for _, dir := range argsWithoutProg {
+		p, err := b.Import(".", dir, 0)
+		if _, ok := err.(*build.NoGoError); ok {
+			continue
+		} else if err != nil {
+			fmt.Printf("build.Import failed due to %v\n", err)
+			continue
+		}
+		for _, pkg := range p.Imports {
+			if pkg == "syscall" || pkg == "unsafe" {
+				fmt.Printf("Package %s/%s importing %s package without appengine build tag is NOT ALLOWED!\n", p.Dir, p.Name, pkg)
+			}
+		}
+	}
+}