lavfi: remove now unused args parameter from AVFilter.init

Conflicts:

	libavfilter/avfilter.c
	libavfilter/vf_drawtext.c
	libavfilter/vf_lut.c
	libavfilter/vf_select.c
	libavfilter/vf_setpts.c
	libavfilter/vsrc_color.c
	libavfilter/vsrc_movie.c

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