The first argument to libxrdp_init() is a intptr_t / tbus value. This
represents the xrdp instance which is using the library, but this value
is always a 'struct xrdp_process' pointer.
This PR replaces the intptr_t with an incomplete type declaration at
the interface between xrdp and libxrdp.
The original intention was probably to provide some separation from
xrdp and the libxrdp code, but in practice this has turned out not to be
useful.
matt335672
c646002779