The create/start split left checkpoint/restore broken in that the create
side was calling runc restore, which fully restores the process to
operation, leaving a call to `runc start` as an error (process already
started). This patch skips process.Start as it is an unnecessary (and
wrong) step for a restored checkpoint.
Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com>