some missing bits in multimedia/v4l_compat

[Luigi Rizzo]

i notice that ports/multimedia/v4l_compat/files/videodev.h has
some differences with respect to the linux equivalent, see e.g.

	http://www.gelato.unsw.edu.au/lxr/source/include/linux/videodev.h

e.g. no #define HAVE_V4L1 1 , 
some missing prototypes, and so on.

Any objection if i fill in some of the missing parts ?

Also, any reason not to make a header for videodev2.h as well

	http://www.gelato.unsw.edu.au/lxr/source/include/linux/videodev2.h

cheers
luigi