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.
Since "libexec" folders under the Cellar are already private per
formula, there's no reason to create an additional folder underneath
for namespacing.
Removed the extra folder level from these formulas.
* Create the empty save folder on install.
* Deparallelize the build, since the master build runs a bunch of
nested makes, and we want the products to come out in-order.
