support/kconfig: ppply upstream nconfig ncurses/ncursesw fix

support/kconfig: ppply upstream nconfig ncurses/ncursesw fix

Buildroot's "make nconfig" command stopped working a while ago on
Gentoo systems. Running the command would result in a crash.

The issue is caused by lxdialog's cflags which are also used to build
nconfig; It would detect *ncursesw* and turn on WIDECHAR support --
but the Makefile would still link to plain *ncurses* while building
nconfig (which was built without WIDECHAR support).

This would cause a crash after using *wattrset* on a WINDOW instance.
WIDECHAR *wattrset* would try to set the _color member in the WINDOW
struct which does not exist in the NON-WIDECHAR ncurses instance. It
would end up clobbering data outside the struct (usually _line entries).

An upstream patch fixes the issue, so we're applying it to Buildroot's
kconfig.

Signed-off-by: Guillermo A. Amaral <g@maral.me>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>