LU-2675 cleanup: remove unused recov_thread.c and llog code

Remove recov_thread.c and the following exported functions:
  llog_cat_process_thread
  llog_obd_origin_add
  llog_catalog_list
  llog_receptor_accept
  llog_origin_connect
  llog_handle_connect
  llog_obd_repl_cancel
  llog_obd_repl_sync
  llog_obd_repl_connect
  llog_get_cat_list
  llog_put_cat_list
  llog_recov_thread_start
  llog_recov_thread_stop

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: I620c641646294fcf697f1e2d4d1f389d71bb3ddd
Reviewed-on: http://review.whamcloud.com/5190
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Liu Xuezhao <xuezhao.liu@emc.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>