swscale: Allow chroma samples to be above and to the left of luma samples

Found-by: Kierank
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit 61af6bebb457c8d9bb00baaccd65a39632437bcd)

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avfilter/vf_scale: Allow chroma samples to be above and to the left of luma samples

Found-by: Kierank
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit e927682e1b258501f3ddecef85801282267277c7)

Conflicts:

	libavfilter/version.h
update for 2.4.1

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