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.
i18n.consoleKeyMap maps to KEYMAP=... in vconsole.conf and `loadkeymap'
in stage1. Both of these accept paths to a keymap file in addition to
a string containing the name of the keymap.
With this commit, it's possible to use your own keymap via:
i18n.consoleKeyMap = ./path/to/something.kmap
