Do not harcode invalid path to ncursesw headers

Adding /usr/include/ncursesw is obviously invalid when
cross-compiling. Since the ncursesw headers are no longer installed in
usr/include/ncursesw/, but directly in usr/include, there is anyway no
need for a special header path.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

Index: b/setup.py
===================================================================
--- a/setup.py
+++ b/setup.py
@@ -1287,7 +1287,6 @@
         panel_library = 'panel'
         if curses_library == 'ncursesw':
             curses_defines.append(('HAVE_NCURSESW', '1'))
-            curses_includes.append('/usr/include/ncursesw')
             # Bug 1464056: If _curses.so links with ncursesw,
             # _curses_panel.so must link with panelw.
             panel_library = 'panelw'