vfs_fruit: remove now unused AppleDouble code for resource fork in xattr

vfs_fruit: remove now unused AppleDouble code for resource fork in xattr

This was only needed to get the resourcefork size via the ad_* AppleDouble
function. This is now done with a fstat on the low level xattr fd (remember,
this is Solaris only code...), so we can remove the xattr special casing from
the AppleDouble functions.

Bug: https://bugzilla.samba.org/show_bug.cgi?id=13968

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
(cherry picked from commit cb9dffa1c66294b6eed85e7576aa99c642d0b541)