generator: use single dict for tracking all enums
generator: use single dict for tracking all enums

A single invokation of the generator only handles processing of one
libvirt API module, so there is no need to use separate dicts for
tracking enums.

Signed-off-by: Daniel P. Berrangé <bb938cf255e055ff3507f2627d214e8e62118fcf@redhat.com>

libvirt/libvirt-python,libvirt/libvirt-python,libvirt/libvirt-python