Use Portage's make.conf parser, allow user-specified extra bind mount po

Attached is a collection of enhancements I'm using in my
local catalyst
installation. In particular:

 - Uses the make.conf parser from portage_utils. This
handles source
directives, multi-line constants, and other goodness the
catalyst one
doesn't.
 - Adds a new directive, "extra_mounts", allows
user-specified bind
mount points. If for some reason an advanced user who's
doing funky
things wants extra bind mounts into the build region, this
permits it.
 - Allow absolute profile paths. Necessary for folks using
custom
profiles not within /usr/portage/profiles. (In my case, that
profile is
coming off a network filesystem for which a bind mount is
set up via the
extra_mounts directive).

If 'yall want me to split patch this out into multiple
pieces, I'd be
glad to do so.

On Mon, 2007-06-11 at 09:38 -0500, Charles Duffy wrote:
> If 'yall want me to split patch this out into multiple
pieces, I'd be
> glad to do so.

Please do.  The things you've added all seem fine and would
likely all
be included, but I much prefer a "one patch per
change" approach so we
can easily back them out, if necessary.

-- 
Chris Gianelloni
Release Engineering Strategic Lead
Alpha/AMD64/x86 Architecture Teams
Games Developer/Council Member/Foundation Trustee
Gentoo Foundation