vp9_sadmxn_x86 only contains SSE2 functions

Rename the file and clean up includes. In the future we would like to
pattern match the files which need additional compiler flags.

Change-Id: I2c76256467f392a78dd4ccc71e6e0a580e158e56
diff --git a/vp9/common/x86/vp9_sadmxn_x86.c b/vp9/common/x86/vp9_sadmxn_sse2.c
similarity index 96%
rename from vp9/common/x86/vp9_sadmxn_x86.c
rename to vp9/common/x86/vp9_sadmxn_sse2.c
index 3072d6d..ed873a5 100644
--- a/vp9/common/x86/vp9_sadmxn_x86.c
+++ b/vp9/common/x86/vp9_sadmxn_sse2.c
@@ -8,13 +8,10 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#include <emmintrin.h>  // SSE2
-#include "./vpx_config.h"
-#include "./vp9_rtcd.h"
+#include <emmintrin.h>  /* SSE2 */
 #include "vpx/vpx_integer.h"
 #include "vpx_ports/emmintrin_compat.h"
 
-#if HAVE_SSE2
 unsigned int vp9_sad16x3_sse2(
   const unsigned char *src_ptr,
   int  src_stride,
@@ -96,5 +93,3 @@
   sad = _mm_add_epi16(sad,  _mm_srli_si128(sad, 8));
   return _mm_cvtsi128_si32(sad);
 }
-
-#endif
diff --git a/vp9/vp9_common.mk b/vp9/vp9_common.mk
index 0d208e9..2b07d5a 100644
--- a/vp9/vp9_common.mk
+++ b/vp9/vp9_common.mk
@@ -118,14 +118,14 @@
 endif
 
 VP9_COMMON_SRCS-$(HAVE_SSE2) += common/x86/vp9_filter_sse2.c
-VP9_COMMON_SRCS-$(HAVE_SSE2) += common/x86/vp9_sadmxn_x86.c
+VP9_COMMON_SRCS-$(HAVE_SSE2) += common/x86/vp9_sadmxn_sse2.c
 ifeq ($(HAVE_SSE2),yes)
 vp9/common/x86/vp9_filter_sse2.c.o: CFLAGS += -msse2
 vp9/common/x86/vp9_loopfilter_x86.c.o: CFLAGS += -msse2
-vp9/common/x86/vp9_sadmxn_x86.c.o: CFLAGS += -msse2
+vp9/common/x86/vp9_sadmxn_sse2.c.o: CFLAGS += -msse2
 vp9/common/x86/vp9_filter_sse2.c.d: CFLAGS += -msse2
 vp9/common/x86/vp9_loopfilter_x86.c.d: CFLAGS += -msse2
-vp9/common/x86/vp9_sadmxn_x86.c.d: CFLAGS += -msse2
+vp9/common/x86/vp9_sadmxn_sse2.c.d: CFLAGS += -msse2
 endif
 
 $(eval $(call asm_offsets_template,\