* fhandler_disk_file.cc (fhandler_disk_file::fchown): Catch an

	* fhandler_disk_file.cc (fhandler_disk_file::fchown): Catch an
	error when changing the user account on a standalone Samba server.
	Explain why.
	* sec_acl.cc (setacl): Accommodate additional parameter to set_file_sd.
	* sec_helper.cc (SECURITY_SAMBA_UNIX_AUTHORITY): Define.
	(well_known_samba_unix_user_fake_sid): Define.
	* security.cc (set_file_sd): Take additional parameter if ownership
	should be changed.  Restrict requested permissions accordingly.
	(set_file_attribute): Accommodate additional parameter to set_file_sd.
	* security.h (well_known_samba_unix_user_fake_sid): Declare.
	(set_file_sd): Align declaration to above change.