Add NoCopy to flag types as not to be copied

See https://github.com/golang/go/issues/8005#issuecomment-190753527 for
more details.

1 files changed, 2 insertions, 0 deletions

diff --git a/net.go b/net.go
index 040fe66..af8e4cd 100644
--- a/net.go
+++ b/net.go
@@ -32,6 +32,8 @@ type PipeListener struct {
 	closed int32
 	conns  chan net.Conn
 	done   chan struct{}
+
+	_ NoCopy
 }
 
 var _ net.Listener = &PipeListener{}