cache_cf.c euid/egid

Hiya all,

Quick easy patch: The attached (I hope I'm getting my attachments and similar
organised properly, I'm still tinkering with mail client setup) is a patch
that makes cache_cf.c not try and figure out nobody and nogroup if it's not
going to use them - ie. if squid is being run as a user instead of as root.
It came up because I don't have a nogroup on my machine.

KevinL
(tinkering around the edges)