Remove an unused define COUNTER_DETECT_ALERTS

The only place this exists in the code is when it is defined.

src/detect.h

@@ -1,4 +1,4 @@
-/* Copyright (C) 2007-2013 Open Information Security Foundation
+/* Copyright (C) 2007-2014 Open Information Security Foundation
  *
  * You can copy, redistribute or modify this Program under the terms of
  * the GNU General Public License version 2 as published by the Free
@@ -43,8 +43,6 @@
 
 #include "detect-mark.h"
 
-#define COUNTER_DETECT_ALERTS 1
-
 #define DETECT_MAX_RULE_SIZE 8192
 
 /* forward declarations for the structures from detect-engine-sigorder.h */