These functions access internals of the opaque object, and do
not need any rpc counterpart.  It could be argued that we should
have provided these when snapshot objects were first introduced,
since all the other vir*Ptr objects have at least a GetName accessor.

* include/libvirt/libvirt.h.in (virDomainSnapshotGetName)
(virDomainSnapshotGetDomain, virDomainSnapshotGetConnect): Declare.
* src/libvirt.c (virDomainSnapshotGetName)
(virDomainSnapshotGetDomain, virDomainSnapshotGetConnect): New
functions.
* src/libvirt_public.syms: Export them.