feat(Core/Misc): remove and replace ACE_Singleton (#2418)

src/server/game/Entities/Creature/CreatureGroups.cpp

@@ -17,6 +17,12 @@ FormationMgr::~FormationMgr()
         delete itr->second;
 }
 
+FormationMgr* FormationMgr::instance()
+{
+    static FormationMgr instance;
+    return &instance;
+}
+
 void FormationMgr::AddCreatureToGroup(uint32 groupId, Creature* member)
 {
     Map* map = member->FindMap();

src/server/game/Entities/Creature/CreatureGroups.h

@@ -28,10 +28,12 @@ typedef std::unordered_map<uint32/*memberDBGUID*/, FormationInfo*>   CreatureGro
 
 class FormationMgr
 {
-    friend class ACE_Singleton<FormationMgr, ACE_Null_Mutex>;
     public:
         FormationMgr() { }
         ~FormationMgr();
+        
+        static FormationMgr* instance();
+        
         void AddCreatureToGroup(uint32 group_id, Creature* creature);
         void RemoveCreatureFromGroup(CreatureGroup* group, Creature* creature);
         void LoadCreatureFormations();
@@ -69,6 +71,6 @@ class CreatureGroup
         bool m_Formed;
 };
 
-#define sFormationMgr ACE_Singleton<FormationMgr, ACE_Null_Mutex>::instance()
+#define sFormationMgr FormationMgr::instance()
 
 #endif