LU-5385: HSM: do not call the JSON log function if no log is open

LU-5385: HSM: do not call the JSON log function if no log is open

llapi_hsm_log_ct_registration() and llapi_hsm_log_ct_progress() are
very expensive (fid2path+allocations). Do not let them do anything
if llapi_hsm_write_json_event() is going to discard the JSON record.

Make llapi_hsm_log_ct_registration() and llapi_hsm_log_ct_progress()
static too.

This is a backport to b2_5.

Lustre-change: http://review.whamcloud.com/11164
Lustre-commit: 35d122fd99c961b0b9fd500b3a78bdc0f5334a97

Signed-off-by: frank zago <fzago@cray.com>
Change-Id: Ib10023968a1bd021694bca6338c0a962f58da19a
Reviewed-on: http://review.whamcloud.com/11164
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: jacques-Charles Lafoucriere <jacques-charles.lafoucriere@cea.fr>
Reviewed-by: Patrick Farrell <paf@cray.com>
Reviewed-by: Faccini Bruno <bruno.faccini@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
(cherry picked from commit 35d122fd99c961b0b9fd500b3a78bdc0f5334a97)
Reviewed-on: http://review.whamcloud.com/11617
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>