DAFS: fix ifdef

DAFS: fix ifdef

there's no DEMAND_ATTACH_ENV ifdef. don't use it.

Reviewed-on: http://gerrit.openafs.org/3484
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit fea0ee62ab854148a354c1aa9ebc5f042448210e)

Change-Id: Ib032930c53b8025e82819e0f82e994b5bdf6c5ba
Reviewed-on: http://gerrit.openafs.org/3794
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>