Merge commit '4753f802'

* commit '4753f802':
  vf_libopencv: use the name 's' for the pointer to the private context
  vf_hqdn3d: use the name 's' for the pointer to the private context
  vf_hflip: use the name 's' for the pointer to the private context
  vf_gradfun: use the name 's' for the pointer to the private context

Conflicts:
	libavfilter/vf_gradfun.c
	libavfilter/vf_hflip.c
	libavfilter/vf_hqdn3d.c

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