Simplifies Makefile by quite a bit.
Added an upstream backport fixing compilation with older OS.
Added a curses patch so -Dauto_features=disabled can work properly.
Signed-off-by: Rosen Penev <rosenp@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/19598
Signed-off-by: Nick Hainke <vincent@systemli.org>
