Deadlock when closing connection when TLS was never established (caused by 268f6355)

(cherry picked from commit 2c0b486de5ba36f7ffed4d5753c60ed64d7192cd)

Source commit: e8d14622ec9ef513400e53b721f50b2538f3af43

source/filezilla/AsyncSslSocketLayer.cpp

@@ -606,7 +606,7 @@ int CAsyncSslSocketLayer::Receive(void* lpBuf, int nBufLen, int nFlags)
 
 void CAsyncSslSocketLayer::Close()
 {
-  if (!m_nShutDown)
+  if (!m_nShutDown && m_bSslEstablished)
   {
     ShutDown();
     while (!ShutDownComplete())