Revert "Merge commit 'ed1a11ed52bbd1f15bb9b0416d69b7924bee3191'"

This reverts commit fc5fe4804fd2ee9a29de502e9431b12d027c0c89, reversing
changes made to ffe33500983983946048def3a6047920d97d957b.

The factoring is broken; it's not calling the ssse3 code anymore, and
calling the mmx2 code with bad alignment. It also broke some FATE
instances.

Conflicts:
	libavfilter/x86/vf_gradfun_init.c
avfilter/vf_gradfun: add emms_c() for mmxext

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