mb_lpf_horizontal_edge AVX2 optimization

This CL contains two AVX2 optimized loop filter functions,
mb_lpf_horizontal_edge_w_avx2_8 and mb_lpf_horizontal_edge_w_avx2_16.

Change-Id: I604e4fe6e99752b7800c2ea98721d97f7e0b931b

vp9/common/vp9_rtcd_defs.sh

@@ -200,7 +200,7 @@ prototype void vp9_loop_filter_vertical_edge "uint8_t *s, int pitch, const uint8
 specialize vp9_loop_filter_vertical_edge mmx neon
 
 prototype void vp9_mb_lpf_horizontal_edge_w "uint8_t *s, int pitch, const uint8_t *blimit, const uint8_t *limit, const uint8_t *thresh, int count"
-specialize vp9_mb_lpf_horizontal_edge_w sse2 neon
+specialize vp9_mb_lpf_horizontal_edge_w sse2 avx2 neon
 
 prototype void vp9_mbloop_filter_horizontal_edge "uint8_t *s, int pitch, const uint8_t *blimit, const uint8_t *limit, const uint8_t *thresh, int count"
 specialize vp9_mbloop_filter_horizontal_edge sse2 neon

vp9/vp9_common.mk

@@ -74,6 +74,7 @@ VP9_COMMON_SRCS-yes += common/vp9_scan.h
 VP9_COMMON_SRCS-$(ARCH_X86)$(ARCH_X86_64) += common/x86/vp9_postproc_x86.h
 VP9_COMMON_SRCS-$(ARCH_X86)$(ARCH_X86_64) += common/x86/vp9_asm_stubs.c
 VP9_COMMON_SRCS-$(ARCH_X86)$(ARCH_X86_64) += common/x86/vp9_loopfilter_intrin_sse2.c
+VP9_COMMON_SRCS-$(HAVE_AVX2) += common/x86/vp9_loopfilter_intrin_avx2.c
 VP9_COMMON_SRCS-$(CONFIG_VP9_POSTPROC) += common/vp9_postproc.h
 VP9_COMMON_SRCS-$(CONFIG_VP9_POSTPROC) += common/vp9_postproc.c
 VP9_COMMON_SRCS-$(HAVE_MMX) += common/x86/vp9_loopfilter_mmx.asm