Close the inherited socket fd

containerd-shim has dup the fd 3, and it don't need fd 3 any more.

Signed-off-by: Shukui Yang <keloyangsk@gmail.com>

cmd/containerd-shim/main_unix.go

@@ -196,7 +196,9 @@ func serve(ctx context.Context, server *ttrpc.Server, path string) error {
 		err error
 	)
 	if path == "" {
-		l, err = net.FileListener(os.NewFile(3, "socket"))
+		f := os.NewFile(3, "socket")
+		l, err = net.FileListener(f)
+		f.Close()
 		path = "[inherited from parent]"
 	} else {
 		if len(path) > 106 {