This reverts commit a87b17f3.
This reduces the amount of non LGPL code, making a relicensing to LGPL
easier

Conflicts:

	libavfilter/vf_yadif.c
	libavfilter/x86/yadif.c
	libavfilter/x86/yadif_template.c
	libavfilter/yadif.h
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>