emotion generic - vlc - make it off by default as 2 video bends is silly

emotion generic - vlc - make it off by default as 2 video bends is silly

as per bug. requiring by DEFAULT 2 video back ends is rather
rediculous. pick one and the others are optional. you could argue xine
now is barely worth it, but it's stable and works and has proven to be
not any real pain.

gst1 is a more optimal and far more complete/featured backend that the
vlc generic one anyway. vlc generic has the bonus of out-of-process,
but gst1 is pretty stable (unlike the 0.1 backend), so let's not make
peolpe install 2 video backends (or possibly 3 or more) just to build
efl out of the box.

this fixes T4284