Implement the deblock

[luctrudeau]

VSX for Deblocking in libvpx can be applied to 3 functions:

• vpx_mbpost_proc_down
  • Merged: https://chromium.googlesource.com/webm/libvpx/+/35e98a70ba65d82f0b94df3f5e453a3a9f0d6365
• vpx_mbpost_proc_ip
  • Merged: https://chromium.googlesource.com/webm/libvpx/+/766d875b9da5c088d62fa50c37194c6e0dc0861a
• vpx_post_proc_down_and_across_mb_row
  • In Review

[luctrudeau]

vpx_post_proc_down_and_across_mb_row just landed. https://chromium.googlesource.com/webm/libvpx/+/656e8ac61e76525bdffcbe03e0a18746ecd74b72

This concludes the VSX support for deblock

Performance gains for POWER8 Model 2.1, of VSX over C are :

• vpx_mbpost_proc_down C time = 195.4 ms, VSX time = 33.7 ms [5.8x]
• vpx_mbpost_proc_ip C time = 188.5ms (±0.2ms), VSX time = 65.2ms (±0.1ms) [2.9x]
• vpx_post_proc_down_and_across_mb_row C time = 121.3 ms (±4.0 ms), VSX time = 9.4 ms (±0.3 ms) [12.9x]