LU-1996 lustre: Flexible changelog format.

Added jobid fields to Changelog records (and extended records). The
CLF_JOBID flags allows to check if the field is present or not (old
format) when reading an entry. Jobids are expressed as 32 chars long,
zero-terminated strings. Updated test_205 in sanity.sh.

Signed-off-by: Henri Doreau <henri.doreau@cea.fr>
Change-Id: Iacfe7099aa520e012535ac48c44793a1b86870a9
Reviewed-on: http://review.whamcloud.com/4060
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Aurelien Degremont <aurelien.degremont@cea.fr>