s3/smbd: set FILE_ATTRIBUTE_DIRECTORY as necessary

s3/smbd: set FILE_ATTRIBUTE_DIRECTORY as necessary

Some VFS modules like GPFS will always return success from
SMB_VFS_GET_DOS_ATTRIBUTES() but only set a subset of the attributes. It
neither sets FILE_ATTRIBUTE_NORMAL nor FILE_ATTRIBUTE_DIRECTORY.

We already handle the case that the VFS stack returns with result==0 and
then add the FILE_ATTRIBUTE_NORMAL, regardless of the type of the
filesystem object. If we want to handle result==0 situation in the
SMB_VFS_GET_DOS_ATTRIBUTES() caller, then do it right by either setting
FILE_ATTRIBUTE_NORMAL or FILE_ATTRIBUTE_DIRECTORY.

Bug: https://bugzilla.samba.org/show_bug.cgi?id=12261

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Fri Sep 16 00:34:43 CEST 2016 on sn-devel-144