LU-9019 obdclass: migrate jobstats to 64 bit time

LU-9019 obdclass: migrate jobstats to 64 bit time

Change all time_t fields for jobstats to time64_t.
Replace cfs_time_current_sec() to avoid the overflow
issues in 2038 with ktime_get_real_seconds().

Change-Id: Icf3af60b9b373acbf5d921add9b4c4d33c77aa61
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: https://review.whamcloud.com/27911
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Niu Yawei <yawei.niu@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>