Add back the internal events into xc backend

Signed-off-by: Jon Ludlam <jonathan.ludlam@citrix.com>
Add internal updates back into xenlight backend

Signed-off-by: Jon Ludlam <jonathan.ludlam@citrix.com>
event_wait now takes a 'local_updates' param

This is so it can be used in the two different contexts required

Signed-off-by: Jon Ludlam <jonathan.ludlam@citrix.com>
Merge pull request #79 from jonludlam/fix_bvt_blocker

Fix bvt blocker