Use includes.h instead of config.h.

This ensures it picks up the definition of DEF_WEAK, the lack of which
can cause compile errors in some cases (eg modern AIX).  From
michael at felt.demon.nl.

openbsd-compat/strndup.c

@@ -16,7 +16,7 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-#include "config.h"
+#include "includes.h"
 #if !defined(HAVE_STRNDUP) || defined(BROKEN_STRNDUP)
 #include <sys/types.h>
 

openbsd-compat/strnlen.c

@@ -18,7 +18,7 @@
 
 /* OPENBSD ORIGINAL: lib/libc/string/strnlen.c */
 
-#include "config.h"
+#include "includes.h"
 #if !defined(HAVE_STRNLEN) || defined(BROKEN_STRNLEN)
 #include <sys/types.h>