Strongly bind security objects to connection object

There is already an implicit connection between them, so let's make
it explicit. This allows easy lookup outside of the processMsg() function.
diff --git a/common/rfb/SSecurityStack.h b/common/rfb/SSecurityStack.h
index dd743d2..8b412bd 100644
--- a/common/rfb/SSecurityStack.h
+++ b/common/rfb/SSecurityStack.h
@@ -26,9 +26,10 @@
 
   class SSecurityStack : public SSecurity {
   public:
-    SSecurityStack(int Type, SSecurity* s0 = 0, SSecurity* s1 = 0);
+    SSecurityStack(SConnection* sc, int Type,
+                   SSecurity* s0 = NULL, SSecurity* s1 = NULL);
     ~SSecurityStack();
-    virtual bool processMsg(SConnection* cc);
+    virtual bool processMsg();
     virtual int getType() const { return type; };
     virtual const char* getUserName() const;
     virtual SConnection::AccessRights getAccessRights() const;