Upgrade to httping 2.3.4 and enable ncurses support

Recent versions of httping have a nice curses-based user interface.  Mac OS X seems to include a usable ncurses library, but the httping configure script and Makefile don't find it because they look for -lncursesw instead of -lncurses.  We change those scripts to drop the "w".
To use the curses user interface, you can use the "-K" option, e.g.
  httping -K -G https://www.google.com