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/SSecurityVncAuth.h b/common/rfb/SSecurityVncAuth.h
index a1d1747..fe00b03 100644
--- a/common/rfb/SSecurityVncAuth.h
+++ b/common/rfb/SSecurityVncAuth.h
@@ -51,8 +51,8 @@
 
   class SSecurityVncAuth : public SSecurity {
   public:
-    SSecurityVncAuth(void);
-    virtual bool processMsg(SConnection* sc);
+    SSecurityVncAuth(SConnection* sc);
+    virtual bool processMsg();
     virtual int getType() const {return secTypeVncAuth;}
     virtual const char* getUserName() const {return 0;}
     virtual SConnection::AccessRights getAccessRights() const { return accessRights; }