Remove all uses of @end in the marshaller, instead just using
the C struct array-at-end-of-struct. To make this work we also remove
all use of @end for switches (making them C unions).
We drop the zero member of the notify message so that we can avoid this
use of @end for a primitive in the marshaller (plus its useless to send
over the wire).
We change the offsets and stuff in the migration messages to real pointers.
Right now we always assume pointers are stored as SPICE_ADDRESS,
i.e. 64bit, independent on the size sent on the network.
This is required for 64bit architectures of course, but slightly overkill
on 32bit architectures, so needs fixing when all SPICE_ADDRESS elements
can be made internal.
We move all message structs from spice-protocol to spice as
we want to be able to change these as needed internally. The
on-network format is no longer defined by these structures anyway,
but rather by the spice protocol description.
