pkg_comp: Dealing with tacit build dependencies

[Mayuresh <mayuresh%acm.org@localhost>]

In practical world, it is not uncommon for build dependencies to be
missing a declaration in the Makefile.

pkg_comp like environment gives a pristine sandbox and such dependencies
start showing up, leading to build failures.

It is impracticable to go on fixing them in all packages. What is a way in
pkg_comp based environment to pre-install some dependencies?

-- 
Mayuresh