ffmpeg mess

@sraue @fritsch FM patches rebased. compile test passed. not tested (vdpau/x11 should be fine. I dont have intel hardware to test vaapi)

sse4 re-added. some ffmpge2 specific stuff dropped (swfilter etc. compare yourself with fernet master)
see https://github.com/stefansaraev/xbmc/commits/fm-master

let me know if I should drop something else.