Fixed closing sub-path of wxGraphicsPath with GDI+ renderer.

Ensure that sub-path being closed contains at least one point.

See #17525.

src/msw/graphics.cpp

@@ -1236,6 +1236,9 @@ void wxGDIPlusPathData::CloseSubpath()
 {
     if( m_figureOpened )
     {
+        // Ensure that sub-path being closed contains at least one point.
+        m_path->AddLine(m_logCurrentPoint, m_logCurrentPoint);
+
         m_path->CloseFigure();
         m_figureOpened = false;
         // Since native GDI+ renderer doesn't move its current point