smbd: make "hide dot files" option work with "store dos attributes = yes"

smbd: make "hide dot files" option work with "store dos attributes = yes"

When using "store dos attributes = yes", the function that reads the
attributes from the xattr get_ea_dos_attribute() will overwrite the
attribute previously set for "hide dot files".

According to smb.conf, "store dos attributes = yes" should only
overwrite the "map XXX" options, but not "hide dot files".

Bug: https://bugzilla.samba.org/show_bug.cgi?id=11645

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): Wed Dec 16 07:21:10 CET 2015 on sn-devel-104