libadouble: allow FILE_SHARE_DELETE in ad_convert_xattr()

libadouble: allow FILE_SHARE_DELETE in ad_convert_xattr()

Not specifying FILE_SHARE_DELETE wasn't done intentionally. Not setting the flag
triggers the following problem:

* client sends a CREATE with delete access

* this triggers a call to open_streams_for_delete() where we check for
conflicting opens on any of the streams of the file or directory

* if the file (or directory) has a stream like ":com.apple.quarantine" the
stream is opened with DELETE_ACCESS and kept open when the next step might:

* if the file (or directory) has a Mac specific :AFP_AfpInfo stream, the
ad_convert() routine in fruit_create_file() is triggered

* ad_convert() checks if the file (or ...) has a sidecar ._ AppleDouble file, if
it has:

* in ad_convert_xattr() we unpack any set of xattrs encoded in the AppleDouble
file and recreate them as streams with the VFS. Now, if any of these xattrs
happens to be converted to a stream that we still have open in
open_streams_for_delete() (see above) we get a NT_STATUS_SHARING_VIOLATION

This error gets passed up the stack back to open_streams_for_delete() so the
client CREATE request fails and the client is unhappy.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15378

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>