r15776: Don't generate ref pointers in Samba4-generated code. There is no point

r15776: Don't generate ref pointers in Samba4-generated code. There is no point
in having pointers for outgoing data when you can already modify the top-level
element.

This can be overridden (temporarily) by specifying the new "keepref"
attribute. Once we've removed keepref from all IDL files, I'll remove this
attribute as well.
(This used to be commit bdc6dd37503ced8322a671d225122ccffbb8bfec)