busybox: preserve ncurses progs/tools

busybox: preserve ncurses progs/tools

The ncurses package installs a full version of clear and reset(tset)
tools.  Preserve these by disabling the options in the busybox config
file.  This removes the need for ncurses to depend on busybox for solely
ordering of target install.

This commit resolves the following python circular dependency with python.
busybox -> libselinux -> python3 -> ncurses -> busybox

Fixes:
http://autobuild.buildroot.net/results/db1/db1e6f3054092fc5576ccab8e04a3b9d74ca9a8c/

Signed-off-by: Matthew Weber <matthew.weber@rockwellcollins.com>
[Thomas: minor tweaks.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>