Log Message:
Update at-spi2-core to 2.6.3:
* Fix a crash when receiving a malformed event.
* Fix atspi_accessible_get_index_in_parent when the parent is not cached
* Fix crash in atspi_device_listener_new_simple.
* registry: Fix a crash when removing hung processes.
* registry: Fix deregistering of applications.
* registry: Fix crash handling DeregisterKeystrokeListener
* Fix some compiler warnings.