Core: Make core build without PCH enabled.

src/server/game/Conditions/ConditionMgr.h

@@ -23,6 +23,7 @@
 #include "Errors.h"
 #include <list>
 #include <map>
+#include <string>
 
 class Player;
 class Unit;

src/server/scripts/Northrend/Nexus/Nexus/boss_magus_telestra.cpp

@@ -16,6 +16,7 @@
  * with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include "GameEventMgr.h"
 #include "ScriptMgr.h"
 #include "ScriptedCreature.h"
 #include "nexus.h"