With years the amount of ifdef have grown up and we are not even sure if the
old code path compiles. Each time we need to update the v4l2 framework to add
the new feature, we break compilation on older kernel. With exception of two
controls in the video orientation control, this patch get rid of all ifdef by
including the latest version of videodev2.h inside GStreamer.
Fixes https://bugzilla.gnome.org/show_bug.cgi?id=723446
