Use: #include <config.h>

Not: #include "config.h"
That way we get the correct config.h when build dir != src dir

strerror.c

@@ -21,7 +21,7 @@
 #include <stdio.h>
 #include <errno.h>
 
-#include "config.h"
+#include <config.h>
 
 #ifndef lint
 static const char rcsid[] = "$Sudo$";