[Mingw-cross-env-list] Binaries using ffmpeg unredistributable

[Martin Lambers]

Hi,

the current ffmpeg build uses --enable-gpl and --enable-version3, which
essentially means that programs that link with ffmpeg must be under
GPLv3 to be redistributable.

Additionally, it uses --enable-nonfree, which means that programs that
link with ffmpeg are not redistributable at all.

The idea was apparently to enable as many features as possible, but
these defaults may be a problem for unsuspecting packages, e.g. packages
that link with ffmpeg only indirectly via OpenSceneGraph or ImageMagick.

It may be a good idea to remove at least --enable-nonfree, and I
personally think that --enable-gpl and --enable-version3 should also be
removed. Packages that want these features may add them locally, and all
others are on the safe side.

(Even then, there is the question of whether distributing binary
packages that contain ffmpeg is completely risk-free, because of the
patent situation described here: <http://ffmpeg.org/legal.html>. To be
completely safe, one might want to disable certain features that are
commonly also disabled in the packages distributed by major GNU/Linux
distributions. But that is a different issue...)

Martin