LU-11116 llog: error handling cleanup

LU-11116 llog: error handling cleanup

llog_cat_new_log() needs some error handling cleanup.
Save and restore thread lgi_cookie when using, to prevent
conflict/corruptions with llog_process_thread().

Signed-off-by: Alexander Boyko <c17825@cray.com>
Change-Id: I12fdfe1a72e77cfeb5ad464b8582db68a7bcfe16
Cray-bug-id: LUS-4780
Reviewed-on: https://review.whamcloud.com/32780
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andriy Skulysh <c17819@cray.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Mike Pershin <mpershin@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>