The AVMedia framework is not deprecated

So no reason to avoid it when building for the Mac App Store
(i.e. when building a sandboxed LibreOffice). (At least I assume it
was because of the deprecatedness of QuickTime that it was conditional
on not building a sandboxed LibreOffice.)

Change-Id: I9d50490aa878ba5e40594b39eac88f23df3ef0a6