[util] fix compilation breakage
[util] fix compilation breakage

On some Linux systems (old ones), there isn't linux/sysinfo.h
header file.  IWYU might suggest to include linux/sysinfo.h
instead of linux/kernel.h if compiling on a new system, so I added
corresponding IWYU pragmas.

I'll address the IWYU issue in a generic way in a separate change
list (so no pragmas would be necessary).  This patch is a quick
fix for the compilation breakage.

Change-Id: Ie9d13815052d8e4c1360db3f94e15ffd77768af5
Reviewed-on: http://gerrit.cloudera.org:8080/8065
Reviewed-by: Adar Dembo <866ca730bfc7f544e3ebce604ceeba4879f23df0@cloudera.com>
Reviewed-by: Andrew Wong <b68e4fdc6430321a6b47400732ff97d7ae91234e@cloudera.com>
Tested-by: Kudu Jenkins

EvilMcJerkface/kudu,andrwng/kudu,EvilMcJerkface/kudu,helifu/kudu,EvilMcJerkface/kudu,EvilMcJerkface/kudu,helifu/kudu,helifu/kudu,InspurUSA/kudu,helifu/kudu,cloudera/kudu,helifu/kudu,helifu/kudu,InspurUSA/kudu,EvilMcJerkface/kudu,andrwng/kudu,EvilMcJerkface/kudu,cloudera/kudu,EvilMcJerkface/kudu,EvilMcJerkface/kudu,InspurUSA/kudu,InspurUSA/kudu,cloudera/kudu,InspurUSA/kudu,andrwng/kudu,andrwng/kudu,cloudera/kudu,helifu/kudu,InspurUSA/kudu,helifu/kudu,EvilMcJerkface/kudu,cloudera/kudu,andrwng/kudu,helifu/kudu,andrwng/kudu,cloudera/kudu,InspurUSA/kudu,cloudera/kudu,cloudera/kudu,andrwng/kudu,InspurUSA/kudu,andrwng/kudu,cloudera/kudu,andrwng/kudu,InspurUSA/kudu