Gerbview: fix incorrect rotation of DCode shape type regular polygon.

The rotation was the opposite of the actual rotation, due to the Y axis
direction (top to bottom) coordinate in gerbview/dcode.cpp
Fixes #16480
https://gitlab.com/kicad/code/kicad/-/issues/16480

gerbview/dcode.cpp

@@ -404,7 +404,7 @@ void D_CODE::ConvertShapeToPolygon( const GERBER_DRAW_ITEM* aParent )
         addHoleToPolygon( &m_Polygon, m_DrillShape, m_Drill, initialpos );
 
         if( !m_Rotation.IsZero() )    // rotate polygonal shape:
-            m_Polygon.Rotate( m_Rotation );
+            m_Polygon.Rotate( -m_Rotation );
 
         break;