tests: include tests.h instead of config.h

Automatically edit tests/*.c files using the following perl one-liner:

perl -0777 -pi -e \
's/#ifdef HAVE_CONFIG_H\n# include "config\.h"\n#endif\n*/#include "tests.h"\n/' \
tests/*.c
diff --git a/tests/readlinkat.c b/tests/readlinkat.c
index 76d0efd..ccfc32d 100644
--- a/tests/readlinkat.c
+++ b/tests/readlinkat.c
@@ -26,10 +26,7 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#ifdef HAVE_CONFIG_H
-# include "config.h"
-#endif
-
+#include "tests.h"
 #include <stdio.h>
 #include <unistd.h>
 #include <sys/syscall.h>