runtime: go fix code for 1.19

We have starting to use golang 1.19, some features are
not supported later, so run `go fix` to fix them.

Fixes: #5750

Signed-off-by: Bin Liu <bin@hyper.sh>

src/runtime/virtcontainers/macvtap_endpoint.go

@@ -1,5 +1,4 @@
 //go:build linux
-// +build linux
 
 // Copyright (c) 2018 Intel Corporation
 //