Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a heterocyclic ring containing oxygen (based on polymers of cyclic esters of polyfunctional acids C09D131/00; based on polymers of cyclic anhydrides of unsaturated acids C09D135/00); Coating compositions based on derivatives of such polymers