autoconf: remove more linux 2.4 references

autoconf: remove more linux 2.4 references

Remove old linux 2.2 and 2.4 references in the autoconf macros left over
from the linux 2.2 and 2.4 days.

Reviewed-on: https://gerrit.openafs.org/13003
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit 833a81eeda6e48ea1ced92169434e843d054c44d)

Change-Id: I3bf407ec084d911cc826b50fc39f48a20eb0fd77
Reviewed-on: https://gerrit.openafs.org/13110
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>