mc: fix build if ncurses have been configured without wide characters

Some distros like poky-tiny set ENABLE_WIDEC=false, which disables wide
character support for ncurses. The new patch fixes the build of mc for
this case.

Since 9000f8033662, NCURSES_WIDECHAR is set explicitly to 1 for musl.
This doesn't work for ENABLE_WIDEC==false. In this case,
NCURSES_WIDECHAR must be set explicitly to 0, as curses.h does not
record whether the ncurses library has actually been built with or
without wide characters.

Fixes: 9000f8033662 ("mc: upgrade 4.8.25 -> 4.8.26")
Signed-off-by: Christian Eggers <ceggers@arri.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>