Fix to bug #549, http://bugs.skysql.com/show_bug.cgi?id=549

Each monitor loops 10 times/second (sleep 100ms) and perform monitoring checks only when monitor's interval is spent. Monitors notice faster if the shutdown flag is set and thus overall shutdown is faster.
hint.c:added missing header
Changed interval from unsigned long to size_t which is guaranteed to be of same size also in windows (if possible).

server/core/hint.c

@@ -17,6 +17,7 @@
  */
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <hint.h>
 
 /**