glusterfsd/main: fix OOM adjustment for older kernels

Milind Changire reported that GlusterFS fails to build on RHEL5
because linux/oom.h is unavailable.

Milind's initial patch disables OOM adjustment completely
for those environments that do not have this header. However,
I'd take another approach that:

1) checks for linux/oom.h in compile-time and defines necessary
constants if the header is not present;
2) checks for available OOM API in /proc in run-time and uses it
accordingly.

This allows OOM to be adjusted properly on RHEL5 (the kernel is pretty new
to present /proc API for that) as well as RHEL6 (the kernel has many thing
backported including new /proc API).

> Reviewed-on: http://review.gluster.org/15587
> Smoke: Gluster Build System <jenkins@build.gluster.org>
> CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
> NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
> Reviewed-by: Niels de Vos <ndevos@redhat.com>
> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>

Change-Id: I1bc610586872d208430575c149a7d0c54bd82370
BUG: 1383692
Signed-off-by: Oleksandr Natalenko <onatalen@redhat.com>
Reviewed-on: http://review.gluster.org/15622
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Smoke: Gluster Build System <jenkins@build.gluster.org>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Niels de Vos <ndevos@redhat.com>

0 files changed, 0 insertions, 0 deletions