Remove SkNx AVX code. It is not really used. Getting in the way of refactoring.

src/core/SkNx.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkNx_DEFINED
 #define SkNx_DEFINED
 
@@ skipping 219 matching lines @@
 typedef SkNx< 8, uint16_t> Sk8h;
 typedef SkNx<16, uint16_t> Sk16h;
 
 typedef SkNx< 4, uint8_t>  Sk4b;
 typedef SkNx< 8, uint8_t>  Sk8b;
 typedef SkNx<16, uint8_t>  Sk16b;
 
 typedef SkNx<4, int> Sk4i;
 
 // Include platform specific specializations if available.
-#if !defined(SKNX_NO_SIMD) && SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_AVX
-    #include "../opts/SkNx_avx.h"
-#elif !defined(SKNX_NO_SIMD) && SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
+#if !defined(SKNX_NO_SIMD) && SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
     #include "../opts/SkNx_sse.h"
 #elif !defined(SKNX_NO_SIMD) && defined(SK_ARM_HAS_NEON)
     #include "../opts/SkNx_neon.h"
 #else
     static inline
     void Sk4f_ToBytes(uint8_t p[16], const Sk4f& a, const Sk4f& b, const Sk4f& c, const Sk4f& d) {
         SkNx_cast<uint8_t>(a).store(p+ 0);
         SkNx_cast<uint8_t>(b).store(p+ 4);
         SkNx_cast<uint8_t>(c).store(p+ 8);
         SkNx_cast<uint8_t>(d).store(p+12);
     }
 #endif
 
 #undef REQUIRE
 
 
 #endif//SkNx_DEFINED