Fix the cl-lib loading stuff

* gnorb-utils.el: Require cl-lib instead of doing the eval-when-compile
  dance for cl.
* gnorb-bbdb.el: No cl
* gnorb-gnus.el: No cl
* gnorb-org.el: No cl
* gnorb-registry.el: Require gnorb-utils

Turns out you're not supposed to do (eval-when-compile (require 'cl))
anymore. Switching to (require 'cl-lib) in gnorb-utils, and make sure
everything else requires that.
Remove incorrect "fix" for Gnus 5.13

* nngnorb.el (nnir-run-gnorb): Apparently I got overenthusiastic about
  this.