cgroups: provide UserConnection for non-linux platforms

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

Author: giuseppe

pkg/cgroups/cgroups_unsupported.go

@@ -4,7 +4,10 @@
 package cgroups
 
 import (
+	"fmt"
 	"os"
+
+	systemdDbus "github.com/coreos/go-systemd/v22/dbus"
 )
 
 // IsCgroup2UnifiedMode returns whether we are running in cgroup 2 cgroup2 mode.
@@ -21,3 +24,8 @@ func UserOwnsCurrentSystemdCgroup() (bool, error) {
 func rmDirRecursively(path string) error {
 	return os.RemoveAll(path)
 }
+
+// UserConnection returns an user connection to D-BUS
+func UserConnection(uid int) (*systemdDbus.Conn, error) {
+	return nil, fmt.Errorf("systemd d-bus is not supported on this platform")
+}