Using pkgs.lib on the spine of module evaluation is problematic
because the pkgs argument depends on the result of module
evaluation. To prevent an infinite recursion, pkgs and some of the
modules are evaluated twice, which is inefficient. Using ‘with lib’
prevents this problem.
This allows to easily override the used PHP package, especially for
example if you want to use PHP 5.5 or if you want to override the
derivation.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
