afsd: include sys/resource.h in afsd_kernel.c

afsd: include sys/resource.h in afsd_kernel.c

With a recent glibc update, sys/wait.h no longer includes
sys/resource.h unless __USE_SVID, __USE_XOPEN or __USE_XOPEN2K8
are set.

Don't rely on the indirect inclusion to get the bits we need;
include it directly in afsd_kernel.c.  This include used to be
there but was dropped when afsd_kernel.c was split off.

Change-Id: I1bfd2e0c340e15ca44472aa89614f088e0c0ce0c
Reviewed-on: http://gerrit.openafs.org/7522
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>