OpenBSD: Remove user.h from dir.c for OpenBSD 4.8

OpenBSD: Remove user.h from dir.c for OpenBSD 4.8

OpenBSD 4.8 no longer needs to include h/user.h in dir.c
and it's presence now gets in the way of the compile so
remove it.

Reviewed-on: http://gerrit.openafs.org/3750
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit e1b0a95352e2e6aa312a526ffcc8a2f77a8fb7df)

Change-Id: I7f46c816f6fcd8ce6018f5e93f2ea0044b221b51
Reviewed-on: http://gerrit.openafs.org/3861
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>