FindCurses: Honor CURSES_NEED_NCURSES when curses is found

Take our CURSES_USE_NCURSES code path when CURSES_NEED_NCURSES is
enabled even if CURSES_CURSES_LIBRARY also happens to be found.
Applied-by: Rolf Eike Beer <eike@sf-mail.de>

Modules/FindCurses.cmake

@@ -40,7 +40,7 @@ find_library(CURSES_CURSES_LIBRARY NAMES curses )
 find_library(CURSES_NCURSES_LIBRARY NAMES ncurses )
 set(CURSES_USE_NCURSES FALSE)
 
-if(CURSES_NCURSES_LIBRARY  AND NOT  CURSES_CURSES_LIBRARY)
+if(CURSES_NCURSES_LIBRARY  AND ((NOT CURSES_CURSES_LIBRARY) OR CURSES_NEED_NCURSES))
   set(CURSES_USE_NCURSES TRUE)
 endif()
 # http://cygwin.com/ml/cygwin-announce/2010-01/msg00002.html