Add ref/deref/new/fileno/open vectors to FDIO_t.

Add ref/deref/new/fileno/open vectors to FDIO_t.
Hide fdOpen/ufdOpen, use {fdio,ufdio}->open throughout.
url.c: Create ref counted abstract urlinfo type with debugging.
url.c: Rename functions to urlNew/urlFree/urlFreeCache for consistency.
rpmio.c: Create ref counted abstract FD_t type with debugging.
rpmio.c: Create private struct _FD_s type.
cpio.c: Create fd[GS]etCpioPos to preserve FD_t abstraction.

CVS patchset: 3414
CVS date: 1999/11/02 14:33:14