solve ncurses problems in a less hacky way

[stebulus]

crosstool-ng autodetects ncurses on the build system, and our environment isn't hermetic, so it can get confused, e.g., detecting ncursesw on Arch Linux. I tried to work around that by shortcircuiting the autodetection (see b34d253), but that caused other problems (see #26). I ultimately worked around it by just not building nconf in crosstool-ng, since we don't need it (see dcd0105), leaving things in a kind of hacky state.

Some preferable end states:

• we fix or figure out how to shortcircuit the autodetection of ncurses in crosstool-ng;
• we don't build ncurses at all, and remove the need for it from crosstool-ng (and the kernel?);
• we make the environment hermetic enough that the autodetection works as-is (I suspect this isn't feasible).