BUG-152 - DestroySocket can leave a freed CServerSocket pointer in the connectionattempts map

Summary

CServerConnect tracks in-flight connection attempts in the connectionattempts map (key: timestamp, value: CServerSocket*). Several socket-destroy paths reach CServerConnect::DestroySocket without first removing the socket from that map: CServerSocket::OnClose while in CS_WAITFORLOGIN, and the early-out branch in ConnectionFailed. After DestroySocket deletes the socket, the map still holds the now-freed pointer, and the next walk of connectionattempts (in AwaitingTestFromIP or AwaitingConnectionToServer) dereferences freed memory and crashes.

Fix

In DestroySocket, before deleting the socket, scan connectionattempts and remove any entry whose value equals the socket being destroyed. This makes the map self-consistent regardless of which destroy path was taken, so it can never retain a dangling pointer.

File: srchybrid/ServerConnect.cpp (CServerConnect::DestroySocket).