I see the problem now, ncurses was recently moved out of the base to an extension - this means its location moved from /usr to /usr/local and "make menuconfig" only looks in /usr.
To get around this problem, you need to symlink /tmp/tcloop/ncurses-dev/usr/local/include/ncurses -> /usr/include/ncurses and symlink the static libs /tmp/tcloop/ncurses-dev/usr/local/lib/lib*.a -> /usr/lib/lib*.a
This is perhaps easiest done by starting emelfm as root