event-test: add ability to run the asyncio event loop
event-test: add ability to run the asyncio event loop

The event test program '--loop' arg is modified to take the name
of an event loop impl to run. eg 'event-test.py --loop asyncio'

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

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