bug#51381: HEIF image format support

[Alan Third]

On Fri, Nov 26, 2021 at 01:02:28PM +0000, Alan Third wrote:
> On Wed, Oct 27, 2021 at 05:13:17PM +0100, Alan Third wrote:
> > 
> > FWIW NSImage (on macOS) is already capable of loading an heic file, if
> > we just point it to it. I thought all we needed to do is add heic to
> > ns_can_use_native_image_api in nsimage.m and then load an image with
> > the type of "heic" or whatever, but it doesn't work and I'm not sure
> > what else I need to do. Probably define heic as a type elsewhere.
> 
> Patch attached. I'm not entirely sure this won't break anything, so
> testing on a platform that already supports heif files would probably
> be a good idea.
> 
> It doesn't support any of the interesting features of heif, for
> example it doesn't allow you to view multiple images (like an animated
> gif), but I have a suspicion the IM/GM code won't support that anyway,
> so no great loss.

Since nobody complained I've pushed this to master.
-- 
Alan Third