Introduce API virNodeDeviceLookupSCSIHostByWWN

Since the name (like scsi_host10) is not stable for vHBA, (it can
be changed either after recreating or system rebooting), current
API virNodeDeviceLookupByName is not nice to use for management app
in this case. (E.g. one wants to destroy the vHBA whose name has
been changed after system rebooting, he has to find out current
name first).

Later patches will support the persistent vHBA via storage pool,
with which one can identify the vHBA stably by the wwnn && wwpn
pair.

So this new API comes.

include/libvirt/libvirt.h.in

@@ -3257,6 +3257,11 @@ int                     virConnectListAllNodeDevices (virConnectPtr conn,
 virNodeDevicePtr        virNodeDeviceLookupByName (virConnectPtr conn,
                                                    const char *name);
 
+virNodeDevicePtr        virNodeDeviceLookupSCSIHostByWWN (virConnectPtr conn,
+                                                          const char *wwnn,
+                                                          const char *wwpn,
+                                                          unsigned int flags);
+
 const char *            virNodeDeviceGetName     (virNodeDevicePtr dev);
 
 const char *            virNodeDeviceGetParent   (virNodeDevicePtr dev);