fails unit tests:
[  FAILED  ] NEON/VP8SubpelVarianceTest.ExtremeRef/0, where GetParam() = (3, 3, 0x14e36d, 0)
[  FAILED  ] NEON/VP8SubpelVarianceTest.Ref/0, where GetParam() = (3, 3, 0x14e36d, 0)

the tests were recently enabled in:
eb88b172 Make vp9 subpixel match vp8

the functions likely haven't changed since being converted from assembly

Change-Id: I6141717b111b8f735f436c160d74270af53ef722