vp9_convolve8_[horiz|vert]_avg

Super basic conversion from the other implementations. Any changes to
one should be trivial to copy over keep in sync.

Change-Id: I1720b4128e0aba4b2779e3761f6494f8a09d3ea8

test/convolve_test.cc

diff --git a/test/convolve_test.cc b/test/convolve_test.cc
index 93d3b01..3320a16 100644
--- a/test/convolve_test.cc
+++ b/test/convolve_test.cc
@@ -549,8 +549,8 @@
 
 #if HAVE_NEON
 const ConvolveFunctions convolve8_neon(
-    vp9_convolve8_horiz_neon, vp9_convolve8_avg_horiz_c,
-    vp9_convolve8_vert_neon, vp9_convolve8_avg_vert_c,
+    vp9_convolve8_horiz_neon, vp9_convolve8_avg_horiz_neon,
+    vp9_convolve8_vert_neon, vp9_convolve8_avg_vert_neon,
     vp9_convolve8_c, vp9_convolve8_avg_c);
 
 INSTANTIATE_TEST_CASE_P(NEON, ConvolveTest, ::testing::Values(