apr: Fix to work with autoconf 2.70

Fix an issue with autoconf 2.70 where duplicate macro includes
caused configure failures.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Ross Burton <ross.burton@arm.com>
(cherry picked from commit 4e5d7c86)
Signed-off-by: Steve Sakoman <steve@sakoman.com>