Core/Game: Move singleton instances into compilation units

* Fixes issues when building shared libraries
  (prevents gcc and clang from providing several instance)

(cherry picked from commit 329225b40d110bed634f8cd0a1ab5c6dc7bbbdd1)

2 files changed, 7 insertions, 5 deletions

diff --git a/src/server/game/World/World.cpp b/src/server/game/World/World.cpp
index 8a29bfe78b0..8496dc08e6e 100644
--- a/src/server/game/World/World.cpp
+++ b/src/server/game/World/World.cpp
@@ -140,6 +140,12 @@ World::~World()
     /// @todo free addSessQueue
 }
 
+World* World::instance()
+{
+    static World instance;
+    return &instance;
+}
+
 /// Find a player in a specified zone
 Player* World::FindPlayerInZone(uint32 zone)
 {
diff --git a/src/server/game/World/World.h b/src/server/game/World/World.h
index bf7d2cb00f7..4f53bfd4592 100644
--- a/src/server/game/World/World.h
+++ b/src/server/game/World/World.h
@@ -538,11 +538,7 @@ struct CharacterInfo
 class World
 {
     public:
-        static World* instance()
-        {
-            static World instance;
-            return &instance;
-        }
+        static World* instance();
 
         static std::atomic<uint32> m_worldLoopCounter;