update vendor

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

vendor/google.golang.org/grpc/test/tools/tools.go

@@ -0,0 +1,34 @@
+// +build tools
+
+/*
+ *
+ * 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.
+ *
+ */
+
+// This package exists to cause `go mod` and `go get` to believe these tools
+// are dependencies, even though they are not runtime dependencies of any grpc
+// package.  This means they will appear in our `go.mod` file, but will not be
+// a part of the build.
+
+package tools
+
+import (
+	_ "github.com/client9/misspell/cmd/misspell"
+	_ "github.com/golang/lint/golint"
+	_ "github.com/golang/protobuf/protoc-gen-go"
+	_ "golang.org/x/tools/cmd/goimports"
+	_ "honnef.co/go/tools/cmd/staticcheck"
+)