s4-dsdb: fix handling of AUX classes in objectclass_sort
This is done by sorting the classes by subClass_order, which will
check if the last structural class is valid to add (in
objectclass_do_add instead checking the last class in the list).
They were being sorted by building a class tree, and adding the
classes to the list in that order. However, AUX classes usually don't
fit into that tree, so LDB_ERR_OBJECT_CLASS_VIOLATION was returned. I
have changed the behavior to sort the classes by subClass_order
instead.
Signed-off-by: Andrew Bartlett <abartlet@samba.org>