vendor: update all dependencies

vendor/google.golang.org/grpc/credentials/internal/syscallconn_appengine.go

@@ -0,0 +1,30 @@
+// +build appengine
+
+/*
+ *
+ * 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.
+ *
+ */
+
+package internal
+
+import (
+	"net"
+)
+
+// WrapSyscallConn returns newConn on appengine.
+func WrapSyscallConn(rawConn, newConn net.Conn) net.Conn {
+	return newConn
+}