widl: Make sure to generate freeing calls for all non-simple structures with pointers and pointers to user marshalled types.

widl: Arrays should have freeing code generated on the server side, even if they are [in] parameters.

Fix the conditions under which pfnFree is called to only include arrays 
that will have been allocated, instead of being pointed to the buffer.

The native version of this DLL contains proxy code for various 
interfaces, but for the moment only servprov.idl is implemented.