httping: disable ncurses support

The new version requires ncursesw support so disable it until we've got
support for it. Fixes:
http://autobuild.buildroot.net/results/588/58840df1254034bf77cde3935fd900d1da13de56/



Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>