Jakub Adam authored Jun 01, 2016 and Olivier Crête committed Jun 01, 2016

"new-selected-pair" may be emitted after "component-state-changed"
to READY, by which time the main loop might have gotten quit in
cb_component_state_changed(). Consequently, cb_new_selected_pair() could
miss to register the selected pair, ultimately leading to an assertion
failure in main().

We should wait for both selected pair and state change events to occur
before stopping the main loop.

Differential Revision: https://phabricator.freedesktop.org/D1044