Comment out ffmpeg for now

We would need to build our own ffmpeg, stripped from patent-encumbred
codecs, which would confuse our users even more. Otherwise we are
going to have real trouble, for instance with Krita in the Windows
Store.

https://www.ffmpeg.org/legal.html says

Q: Is it perfectly alright to incorporate the whole FFmpeg core into my own commercial product?

A: You might have a problem here. There have been cases where companies
have used FFmpeg in their products. These companies found out that once
you start trying to make money from patented technologies, the owners
of the patents will come after their licensing fees. Notably, MPEG LA
is vigilant and diligent about collecting for MPEG-related technologies.

So we really need to consider this again :-(

CCMAIL:kimageshop@kde.org