[File] qemu disk file format

[Christoph Biedl]

Steve Grubb wrote...

> It doesn't know what it's looking at. The text in magic/Magdir/virtual is 
> kind of complicated or I would take a stab at patching this. The shared-mime-
> info package seems to think it should be application/x-qemu-disk.

The related change ("Add mime type for qemu files (Steve Grubb)")
however triggers a build failure:

| ../src/file -C -m magic
| magic/virtual, 223: Warning: Current entry does not yet have a description for adding a MIME type

    Christoph