(Thomas Sibley): Tell Storable to freeze and thaw CODE refs

By default it won't for security.

This reverts commit 5dd8e967998c8ccc3305c5c41c4c2d6f4b6a3395: "skip
tests if the cloning class used happens to be Storable, see bug #3447".

The failing tests from Redmine issue #3447, t/Seq/Seq.t and
t/SeqTools/SeqUtils.t, pass for me both with and without Clone
available.  I tested using -MDevel::Hide=-from:children,Clone.