Merge changes I40454d26,I892e76d5,I865ab3f9,I4a4bec17,I61c4351e,I37eb3559,I1031c556,I8c8f1f42

* changes:
  delete vp9_loopfilter_sse2.asm
  vp9_loopfilter_intrin_sse2: cosmetics: fix indent
  delete x86/vp9_loopfilter_x86.h
  vp9_loopfilter_intrin_sse2: make some funcs static
  vp9_loopfilter_intrin_sse2: remove unused uv funcs
  vp9_loopfilter: remove uv function typedef
  filter_block_plane: reuse some constants
  vp9_loopfilter.c: make some functions static