Log Message:
Update at-spi2-core to 2.8.0

* Add atspi_accessible_get_object_locale (BGO#694368).
* Start the bus launcher in the initialization phase (BGO#694984).
* Removed a debug print that was accidentally included in 2.7.5.
* Add ATSPI_ROLE_LEVEL_BAR to correspond to the new atk role.
* Fix various compiler warnings.
* Fix some ref count leaks.
* Some functions that return accessibles now propagate errors.
* Atspi_accessible_get_index_in_parent no longer returns -1 if the object's
  parent is not cached (BGO#688057).
* re-register keystroke listeners if the registry goes away and then returns.
* Fix atspi_device_listener_new_simple.
* Fix some compiler warnings.
* Build: use gobject-introspection's Makefile instead of rolling our own.
* Fix a crash when parsing events without detail when there is a listener
  for the event that names a specific detail value.
* Fix crash when removing hung processes.
* Fix deregistering of applications.
* A few documentation fixes.
* Only call an event listener once per event, even if the listener registered
  for both the event and a superset of the event.
* Don't distribute dbind-config.h (BGO#688083).
* Fix gtk-doc for Atspi-Registry (BGO#688224).
* Some introspection fixes to make vapigen happy (BGO#688223).
* [registry] Fixed a crash handling DeregisterKeystrokeListener.
* Update the cache in response to role change notifications (BGO#685469).
* Don't output a warning when a p2p connection isn't available.