Use better security method description when using VeNCrypt

The sub-modules generally provide a better description than just the
short security method name.

common/rfb/CSecurityVeNCrypt.cxx

@@ -191,6 +191,13 @@ bool CSecurityVeNCrypt::processMsg(CConnection* cc)
   return csecurity->processMsg(cc);
 }
 
+const char* CSecurityVeNCrypt::description() const
+{
+  if (csecurity)
+    return csecurity->description();
+  return "VeNCrypt";
+}
+
 bool CSecurityVeNCrypt::isSecure() const
 {
   if (csecurity && csecurity->isSecure())

common/rfb/CSecurityVeNCrypt.h

@@ -38,7 +38,7 @@ namespace rfb {
     ~CSecurityVeNCrypt();
     virtual bool processMsg(CConnection* cc);// { return true; }
     int getType() const {return chosenType;}
-    virtual const char* description() const { return secTypeName(chosenType); }
+    virtual const char* description() const;
     virtual bool isSecure() const;
 
   protected: