Fixes a layout bug with the COMBINING GRAVE ACCENT ' ̀'

* The layout engine failed to calculate correctly the length
  of the line if that character is used in the last position.

if HORIZONTAL_ALIGNMENT is END, this is a problem.

    example)
    Property::Map backgroundMap;
    backgroundMap["color"] = Color::RED;
    backgroundMap["enable"] = true;
    TextLabel testLabel = TextLabel::New( "Àwọn àgbétẹ́lẹ̀");
    testLabel.SetAnchorPoint( AnchorPoint::TOP_LEFT );
    testLabel.SetProperty(TextLabel::Property::POINT_SIZE, 34.f);
    testLabel.SetPosition(100.f, 100.f);
    testLabel.SetSize( 544.f, 100.f);
    testLabel.SetProperty(TextLabel::Property::HORIZONTAL_ALIGNMENT, "END");
    testLabel.SetProperty(Toolkit::DevelTextLabel::Property::BACKGROUND, backgroundMap);
    stage.Add( testLabel );

Change-Id: Ic66fd96cc010eada7187502b9b65e2b408eff2cd