Align statistics to cache lines

Aligning the statistics object indices to cache line size reduces the CPU
overhead of gathering the statistics. This allows the statistics to more
accurately measure the polling system without the measurement affecting
the outcome.

server/core/test/test_utils.h

@@ -20,7 +20,7 @@
 #include <maxscale/housekeeper.h>
 #include <maxscale/maxscale_test.h>
 #include <maxscale/log_manager.h>
-#include <maxscale/statistics.h>
+#include "../maxscale/statistics.h"
 
 void init_test_env(char *path)
 {