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.