Signed-off-by: NNitesh Konkar <nitkon12@linux.vnet.ibm.com>

Node device lifecycle event API entry points for registering and
deregistering node deivce events, as well as types of events
associated with node device.
These entry points will be used for implementing asynchronous
lifecycle events.

Node device API:
virConnectNodeDeviceEventRegisterAny
virConnectNodeDeviceEventDeregisterAny
virNodeDeviceEventLifecycleType which has events CREATED and DELETED

There are also a couple that were very uninformatively just logging
the value of the pointer rather than the string itself:

* the "name" arg to virNodeDeviceLookupByName()
* wwnn and wwpn args to virNodeDeviceLookupSCSIHostByWWN()

All char*'s that make sense should now have their contents logged
rather than the pointer, and all %s args should now be inside
NULLSTR().

Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>

Introduce a src/libvirt-nodedev.c file to hold all the
methods related to the virNodeDevice type.