Build ncurses on OSX

Make ncurses compile on osx. Patch is the one taken from Homebrew: https://github.com/Homebrew/homebrew-dupes/commit/b1e3cb176c32beeada27c543ce921e6d941fc9a2#diff-01913bb69a09fa43b28f664fe9a322e8R15 (https://trac.macports.org/export/103963/trunk/dports/devel/ncurses/files/constructor_types.diff)