avconv: Support VDA hwaccel

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
Merge commit '1839fafa951308237c4672ffd9a94f927b26eac7'

* commit '1839fafa951308237c4672ffd9a94f927b26eac7':
  avconv: Support VDA hwaccel

Conflicts:
	Makefile

Merged-by: Michael Niedermayer <michaelni@gmx.at>