LU-6542 lnet: handle cYAML out of memory error

LU-6542 lnet: handle cYAML out of memory error

in cYAML_build_error() there is a potential on run out of memory
scenario, that it is ignored and no error is built.
In this case print out a properly formated YAML error message
indicating fatal error

Signed-off-by: Amir Shehata <amir.shehata@intel.com>
Change-Id: Id9159044acafb38bd022f421a997fa2d2f1841e8
Reviewed-on: http://review.whamcloud.com/15778
Tested-by: Jenkins
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>