* packages/gnorb: Don't require cl. Fix up compilation errors.

* packages/gnorb: Don't require cl.  Fix up compilation errors.

* packages/gnorb/gnorb-bbdb.el: Don't require cl unnecessarily.
Don't fail compilation just because bbdb is not available yet.
(gnorb-bbdb-tag-agenda): Fix typo.
* packages/gnorb/gnorb-gnus.el: Don't require cl unnecessarily.
(gnorb-gnus-view): Fix var binding.
* packages/gnorb/gnorb-org.el: Don't require cl unnecessarily.
* packages/gnorb/gnorb-utils.el: Don't require cl unnecessarily.
But do require mailcap.
(gnorb-msg-id-to-group): Remove dead code.