Remove invalid memset in ServerPresence (#709)

The use of sizeof is incorrect here since `this` is a pointer and sizeof is used on the pointer directly, instead of what the pointer points to.
It seems to work without issue due to padding but could cause issues if an instanced class like `std::string` gets nulled.

Author: Jan200101

primedev/server/serverpresence.h

@@ -19,10 +19,7 @@ struct ServerPresence
 	int m_iPlayerCount;
 	int m_iMaxPlayers;
 
-	ServerPresence()
-	{
-		memset(this, 0, sizeof(this));
-	}
+	ServerPresence() {}
 
 	ServerPresence(const ServerPresence* obj)
 	{