People have asked for such a thing before, but it'd be quite difficult to do reliably --- particularly inside function bodies, which aren't normally parsed at all during a dump/restore. If you're willing to accept a 95% solution, running the pg_restore output through "sed" would likely work fairly well. I'd personally want to diff the before-and-after scripts before applying though :-)
Another 95% solution, if both schemas are on the same server, google for function clone schema, you´ll find some of them. They create tables, functions, sequences, views, ...