Use pkg-config to set linker and include flags.

Force including and linking against ncurses instead of ncursesw. This is only useful on systems that have the ncursesw package installed incorrectly. On most systems this will cause compile- or run-time errors.

Force using the newtype'd pointer hooks introduced in c2hs 0.18.1. This is only necessary when building with c2hs==0.18.1, as 0.18.2 and later can be auto-detected.