Update license headers for cstrike modules.

dlls/cstrike/csx/sdk/amxxmodule.h

@@ -1,7 +1,16 @@
-/*
- * AMX Mod X Module Interface Functions
- * This file may be freely used
-*/
+// vim: set ts=4 sw=4 tw=99 noet:
+//
+// AMX Mod X, based on AMX Mod by Aleksander Naszko ("OLO").
+// Copyright (C) The AMX Mod X Development Team.
+//
+// This software is licensed under the GNU General Public License, version 3 or higher.
+// Additional exceptions apply. For full license details, see LICENSE.txt or visit:
+//     https://alliedmods.net/amxmodx-license
+//
+
+//
+// Module SDK
+//
 
 // prevent double include
 #ifndef __AMXXMODULE_H__