This library is shared between GHC, ghc-pkg, and other boot
libraries.

A note about "GHC.Unit.Database": it only deals with the subset of
the package database that the compiler cares about: modules
paths etc and not package metadata like description, authors
etc. It is thus not a library interface to ghc-pkg and is *not*
suitable for modifying GHC package databases.

The package database format and this library are constructed in
such a way that while ghc-pkg depends on Cabal, the GHC library
and program do not have to depend on Cabal.