Avoid keeping @docker_cli_[UUID] files

Seems that OpenBSD behaves like darwin and requires to unlink all
socket, after it was used.

Tested on OpenBSD 7.4

Signed-off-by: Kirill A. Korinsky <kirill@korins.ky>
(cherry picked from commit 2c214241fa)
Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>

cli-plugins/socket/socket_nodarwin.go

@@ -1,4 +1,4 @@
-//go:build !darwin
+//go:build !darwin && !openbsd
 
 package socket
 
@@ -15,5 +15,6 @@ func listen(socketname string) (*net.UnixListener, error) {
 
 func onAccept(conn *net.UnixConn, listener *net.UnixListener) {
 	// do nothing
-	// while on darwin we would unlink here; on non-darwin the socket is abstract and not present on the filesystem
+	// while on darwin and OpenBSD we would unlink here;
+	// on non-darwin the socket is abstract and not present on the filesystem
 }

cli-plugins/socket/socket_openbsd.go

@@ -0,0 +1,19 @@
+package socket
+
+import (
+	"net"
+	"os"
+	"path/filepath"
+	"syscall"
+)
+
+func listen(socketname string) (*net.UnixListener, error) {
+	return net.ListenUnix("unix", &net.UnixAddr{
+		Name: filepath.Join(os.TempDir(), socketname),
+		Net:  "unix",
+	})
+}
+
+func onAccept(conn *net.UnixConn, listener *net.UnixListener) {
+	syscall.Unlink(listener.Addr().String())
+}