brewkit.rb changes ENV destructively, so lets not do that everytime a formula
is required. Now it's possible for other tools to require a formula
description without worrying about side-effects.
Signed-off-by: Max Howell <max@methylblue.com>
I made everything compile, however I haven't tested it yet as I have a mix of
MacFUSE installations and am thus not a good test case!
