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/CSecurity.h b/common/rfb/CSecurity.h
index 4bf4b38..2e703c6 100644
--- a/common/rfb/CSecurity.h
+++ b/common/rfb/CSecurity.h
@@ -44,8 +44,9 @@
   class CConnection;
   class CSecurity {
   public:
+    CSecurity(CConnection* cc) { this->cc = cc; }
     virtual ~CSecurity() {}
-    virtual bool processMsg(CConnection* cc)=0;
+    virtual bool processMsg() = 0;
     virtual int getType() const = 0;
     virtual const char* description() const = 0;
     virtual bool isSecure() const { return false; }
@@ -55,6 +56,9 @@
      * It MUST be set by viewer.
      */
     static UserPasswdGetter *upg;
+
+  protected:
+    CConnection* cc;
   };
 }
 #endif