posix file: Match newer warning wording

For compatibility with GNAT GPL 2017.

Change-Id: I1b4b914aa4964967b1c598ef5ca303410bd413ec
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/20256
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
1 file changed