Back out MFC of "eradicate caddr_t".

Back out MFC of "eradicate caddr_t".
Turn's out Kris' suspisions were right - from a suttle code compatability
point of view.  Robert Watson found that ARLA code had something like this:
	typedef int (*foo_t)(caddr_t); ... foo_t fred;
The compile gets all snarky when it finds int fred(void *) { .. }.