Remove old, dead compat code.

We no longer need to od these things conditionally, and the fallbacks
are to 4.2BSD era defaults, which nobody uses anymore. Vixie cron has
diverged from upstream anyway in our tree, and it's not clear there's
actually a viable upstream anymore. Plus, we don't follow the
vendor-supplied code pattern here.

I'm doing this to reduce false positives from grep.