codec: opus: fix oob read (cid #1062575)

Opus supports up to 255 channels
demux: ogg: don't double read

wrong fix for cid #1048729
bs_read in __MAX macro forwards read pointer twice
macosx: implement simpler and generic drop view for all drag / drop operations

- Use the new VLCDragDropView for both CAS and main window drop zone.
  This implements a drop highlight border the same way as in playlist view.
- Remove Brushed Metal Image view and its own drop implementation.
  When having a image view inside a drop zone, you need to use
  VLCDropDisabledImageView which disables the own drop handling of NSImageView.
- Removed more unneeded drop implementations for subviews from CAS
MMDevice: simplify Close in WinRT mode

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>