* commit '7f839595':
  vf_crop: use the name 's' for the pointer to the private context
  vf_boxblur: use the name 's' for the pointer to the private context
  vf_blackframe: use the name 's' for the pointer to the private context

Conflicts:
	libavfilter/vf_blackframe.c
	libavfilter/vf_boxblur.c
	libavfilter/vf_crop.c
Merged-by: Michael Niedermayer <michaelni@gmx.at>