Don't make redundant launch while updating configuration

If the configuration changed the same time when the app was launched,
from ActivityStackSupervisor#realStartActivityLocked we updated
configuration, which lead to resuming top activity in focused stack.
This caused second redundant launch of already launching activity.

Bug: 29516875
Change-Id: I2babe1936dfb53b5a440deee34874731913db2eb