LU-9934 build: address issues raised by gcc7

LU-9934 build: address issues raised by gcc7

Starting with gcc version 7 several platforms have enabled new
flags to report potential problems when compling code. For lustre
much of the reported problems deal with potential buffer overruns.
Also we have unused data structures and are not properly
initializing some data structures.

Change-Id: I10243ea88f2c726032d179febdbf26f28de13715
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: https://review.whamcloud.com/30376
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>