Core/DB Layer: Fix a memory leak.

src/server/shared/Database/MySQLConnection.cpp

@@ -68,9 +68,13 @@ MySQLConnection::~MySQLConnection()
     }
 
     mysql_close(m_Mysql);
+    MySQL::Thread_End();
     Unlock();   /// Unlock while we die, how ironic
 }
 
+//! Can be called synchronously in DatabaseWorkerPool, in which thread-specific variables initialized in the main thread
+//! are deallocated.
+//! Can also be called by worker threads, in which their respective thread-specific variables are deallocated.
 void MySQLConnection::Close()
 {
     /// Only close us if we're not operating