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
Move the details of how to capture to the device object. Remove the
v4l2src_calls.[ch] files because they are empty now.
Provide two simple methods to get and return a buffer to the device.
Also do a slow copy when the buffer is not from our pool.
