LU-3427 build: fix 'error handling' issues

LU-3427 build: fix 'error handling' issues

Fix 'error handling' issues found by Coverity version 6.5.1:
Unchecked return value (CHECKED_RETURN)
Calling function without checking return value.

Signed-off-by: Sebastien Buisson <sebastien.buisson@bull.net>
Change-Id: Id0d7c6f5fdddcc5ba9b78f9410f30d9bfc39dac8
Reviewed-on: http://review.whamcloud.com/6510
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Tested-by: Hudson
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>