macosx: Improve drawing of VLCHUDSliderCell
macosx: Improve drawing of VLCHUDSliderCell

Signed-off-by: Felix Paul Kühne <af44a38b4065def9b90f0b66e4658837dd45b77d@videolan.org>

xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc