scripts: create CT_HEADERS_DIR

"${CT_SYSROOT_DIR}/usr/include" is only for "${CT_USE_SYSROOT}" = "y".
We should also mkdir when "${CT_USE_SYSROOT}" != "y".
"${CT_HEADERS_DIR}" can support both cases.

Signed-off-by: Zhenqiang Chen <zhenqiang.chen@linaro.org>
(transplanted from bdff4164a1227ebdd538e0ad3c9b6862b3c5a253)

#!/bin/sh

# Needed for systems without gettext

$* -xc -o /dev/null - > /dev/null 2>&1 << EOF

#include <libintl.h>

int main()

{

	gettext("");

	return 0;

}

EOF

if [ ! "$?" -eq "0"  ]; then

	echo -DKBUILD_NO_NLS;

fi