Windows: avoid preprocessor symbols redefinitions

Windows: avoid preprocessor symbols redefinitions

In afskfw.h avoid preprocessor symbol redefinitions when
RD_AP_TIME or INTK_BADPW are already defined.

Change-Id: If123c7a7564c5dbe509ad107f2c856e96e562d33
Reviewed-on: http://gerrit.openafs.org/4558
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-on: http://gerrit.openafs.org/4566