ports/117173: graphics/opencv does not compile if ffmpeg option is chosen

[soralx at cydem.org]

> > Could you please test if this issue still exists with an fresh ports
> > tree? Thanks for your report.
> 
> With latest ffmpeg and ports tree as of today, the problem persists.

...and by latest ffmpeg I mean the one from the ports.

> [SorAlx]  ridin' VS1400

[SorAlx]  ridin' VS1400