deinterlace: add SSE2 replacement for removed MMX/MMXEXT

This MR was originally purposed for purging all MMX/MMXEXT code from the codebase, including a conversion of MMX/MMXEXT in deinterlace to SSE2. Due to the android build issue with the latter discussed below holding everything up, most of the work was broken up into separate MRs, including a simple purge of MMX/MMXEXT from deinterlace in !424 (merged).

This MR now simply contains an SSE2 replacement for the purged deinterlace MMX/MMXEXT.