RWX on a file does not imply DELETE access

RWX on a file does not imply DELETE access

Without this the changed checks in can_delete_file_in_directory give DELETE
access where there is none. So we can end up granting the ntcreate&x preparing
the unlink where we should not, which leads to a NT_STATUS_ACCESS_DENIED at
close time later, which in turn does *not* give the access denied error message
in the Windows GUI.

can_delete_file_in_directory will grant access now by looking at the directory
permissions.