gRPC migration

Change-Id: I3129ae27d7ee12a23c7046f0d877e8064f2fd7f4
diff --git a/vendor/golang.org/x/sys/windows/empty.s b/vendor/golang.org/x/sys/windows/empty.s
index 69309e4..fdbbbcd 100644
--- a/vendor/golang.org/x/sys/windows/empty.s
+++ b/vendor/golang.org/x/sys/windows/empty.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !go1.12
 // +build !go1.12
 
 // This file is here to allow bodyless functions with go:linkname for Go 1.11