Bug 2116: Prevent opening tunneled sessions in PuTTY from Login dialog as it cannot work

https://winscp.net/tracker/2116
(cherry picked from commit 8bcd6f625bb3f9216a3ff6b70831469955f4319e)

# Conflicts:
#	source/forms/Login.cpp

Source commit: 257b47ae2a985de2f43586d1afed6983b14018d5

source/forms/Login.cpp

@@ -1213,7 +1213,7 @@ void __fastcall TLoginDialog::ActionListUpdate(TBasicAction * BasicAction,
   }
   else if (Action == PuttyAction)
   {
-    Action->Enabled = (NewSiteSelected || SiteSelected) && CanLogin();
+    Action->Enabled = (NewSiteSelected || SiteSelected) && CanLogin() && !GetSessionData()->Tunnel;
   }
   else if (Action == SaveSessionAction)
   {