Clean up dead xfermode opts code.

src/core/SkXfermode.cpp

Index: src/core/SkXfermode.cpp
diff --git a/src/core/SkXfermode.cpp b/src/core/SkXfermode.cpp
index e0124b9b2ffb0ead4f9d0430e9c98417dfb42a4b..54f1df488f88fefefbaa59b65f1774a824af5fbc 100644
--- a/src/core/SkXfermode.cpp
+++ b/src/core/SkXfermode.cpp
@@ -7,7 +7,6 @@
  */
 
 #include "SkXfermode.h"
-#include "SkXfermode_opts_SSE2.h"
 #include "SkXfermode_proccoeff.h"
 #include "Sk4pxXfermode.h"
 #include "SkColorPriv.h"
@@ -16,13 +15,8 @@
 #include "SkPMFloat.h"
 #include "SkReadBuffer.h"
 #include "SkString.h"
-#include "SkUtilsArm.h"
 #include "SkWriteBuffer.h"
 
-#if !SK_ARM_NEON_IS_NONE
-    #include "SkXfermode_opts_arm_neon.h"
-#endif
-
 #define SkAlphaMulAlpha(a, b)   SkMulDiv255Round(a, b)
 
 static inline unsigned saturated_add(unsigned a, unsigned b) {