Add Neon optimized loop filter functions.

- Added vp9_loop_filter_horizontal_edge_neon and
  vp9_loop_filter_vertical_edge_neon.
- The functions are based off the vp8 loopfilter
  functions.
- Matches x86 md5 checksum.

Change-Id: Id1c4dddb03584227e5ecd29f574a6ac27738fdd0
diff --git a/vp9/vp9_common.mk b/vp9/vp9_common.mk
index 7a74833..7eac3a1 100644
--- a/vp9/vp9_common.mk
+++ b/vp9/vp9_common.mk
@@ -100,6 +100,8 @@
 VP9_COMMON_SRCS-$(HAVE_SSE2) += common/x86/vp9_idct_intrin_sse2.c
 VP9_COMMON_SRCS-$(HAVE_SSE2) += common/x86/vp9_sadmxn_sse2.c
 
+VP9_COMMON_SRCS-$(HAVE_NEON) += common/arm/neon/vp9_loopfilter_neon$(ASM)
+
 $(eval $(call asm_offsets_template,\
          vp9_asm_com_offsets.asm, $(VP9_PREFIX)common/vp9_asm_com_offsets.c))