Only register a container once it's successfully started. This avoids a
race condition where the daemon is killed while in the process of
calling `libcontainer.Container.Start`, and ends up killing -1.
There is a time window where the container `initProcess` is not set, and
its PID unknown. This commit fixes the race Engine side.
Signed-off-by: Arnaud Porterie <arnaud.porterie@docker.com>
Upstream-commit: ad2fa3945997905760a4c7ef0444580ffb4b939a
Component: engine
c66cb2a6ce