[bug#29054] frei0r-plugins + build ffmpeg with frei0r

[ng0]

This adds frei0r-plugins on my path to pitivi.
frei0r is also an optional dependency for ffmepg
so I added it to ffmepg and removed the "TODO" style
comment about it in ffmepg.
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0001-gnu-Add-frei0r-plugins.patch
Description: Text document

0002-gnu-ffmpeg-Configure-with-frei0r.patch
Description: Text document

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