PCH build fix. Again.

(( Alright, you made me waste 20 minutes of my life on a full nonPCH rebuild of the core now. ))
(( I hope you're happy. ))

src/server/game/Scripting/ScriptSystem.cpp

@@ -20,6 +20,7 @@
 #include "ObjectMgr.h"
 #include "DatabaseEnv.h"
 #include "ScriptMgr.h"
+#include "Creature.h"
 
 SystemMgr* SystemMgr::instance()
 {
@@ -153,3 +154,8 @@ void SystemMgr::LoadScriptSplineChains()
         TC_LOG_INFO("server.loading", ">> Loaded spline chain data for %u chains, consisting of %u splines with %u waypoints in %u ms", chainCount, splineCount, wpCount, GetMSTimeDiffToNow(oldMSTime));
     }
 }
+
+SplineChain const* SystemMgr::GetSplineChain(Creature const* who, uint8 id) const
+{
+    return GetSplineChain(who->GetEntry(), id);
+}