Occasionally, GATHERING_STATE_COMPLETE was obtained in _update_ice_
gathering_state_task() before consuming all the tasks for local ICE
candidates in _on_local_ice_candidate_task(). It missed notifying the
'ice-gathering-state' signal for gathering completion.
This patch fixes it.
Change-Id: Ie0a997e6976f48b876cb0741f488826a0c172116
Signed-off-by: Sangchul Lee <sc11.lee@samsung.com>