Fix the libpod.LabelVolumePath stub

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

libpod/util_unsupported.go

@@ -25,7 +25,7 @@ func assembleSystemdCgroupName(baseSlice, newSlice string) (string, error) {
 
 // LabelVolumePath takes a mount path for a volume and gives it an
 // selinux label of either shared or not
-func LabelVolumePath(path string, shared bool) error {
+func LabelVolumePath(path string) error {
 	return define.ErrNotImplemented
 }