LU-6634 llog: destroy plain llog if init fails

LU-6634 llog: destroy plain llog if init fails

llog_cat_add_rec() should destroy the plain llog
in the same transaction if initialization of that
failed. also, llog_osd_write_rec() should check
the object still exists as it's possible that
another thread failed to initialize and destroyed
the llog.

Change-Id: I7b823d34b32b5caaf0cc17b4cfe278a07a78ec15
Signed-off-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-on: http://review.whamcloud.com/16427
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: wangdi <di.wang@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>