save start error into State.Error

when a container failed to start, saves the error message into State.Error so
that it can be retrieved when calling `docker inspect` instead of having to
look at the log

Docker-DCO-1.1-Signed-off-by: Daniel, Dao Quang Minh <dqminh89@gmail.com> (github: dqminh)
Merge pull request #8315 from dqminh/save-start-error

Save start error into State.Error when the container fails to start