fixed zone creation problem with DRC OFF and an other minor bug

pcbnew/ratsnest.cpp

@@ -505,7 +505,7 @@ void WinEDA_BasePcbFrame::Build_Board_Ratsnest( wxDC* DC )
     // erase the ratsnest displayed on screen if needed
     for( unsigned ii = 0; ii < m_Pcb->GetRatsnestsCount(); ii++ )
     {
-        if( !g_Show_Ratsnest && DC )  // Clear VISIBLE flag
+        if( !g_Show_Ratsnest )  // Clear VISIBLE flag
             m_Pcb->m_FullRatsnest[ii].m_Status &= ~CH_VISIBLE;
 
         if( DC )

pcbnew/zones_by_polygon.cpp

@@ -598,7 +598,7 @@ int WinEDA_PcbFrame::Begin_Zone( wxDC* DC )
         if( zone->GetCornerPosition( ii - 1 ) != zone->GetCornerPosition( ii ) )
         {
             if( (Drc_On && m_drc->Drc( zone, ii - 1 ) == OK_DRC)
-               || !zone->IsOnCopperLayer() ) // Ok, we can add a new corner
+                || !Drc_On || !zone->IsOnCopperLayer() ) // Ok, we can add a new corner
             {
                 zone->AppendCorner( GetScreen()->m_Curseur );
                 SetCurItem( zone );     // calls DisplayInfo().