Specialize Sk2d for ARM64

src/core/SkPMFloat.h

 #ifndef SkPM_DEFINED
 #define SkPM_DEFINED
 
 #include "SkTypes.h"
 #include "SkColor.h"
 #include "SkColorPriv.h"
 #include "Sk4x.h"
 
 #if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
     #include <immintrin.h>
-#elif defined(__ARM_NEON__)
+#elif defined(SK_ARM_HAS_NEON)
     #include <arm_neon.h>
 #endif
 
 // A pre-multiplied color storing each component in the same order as SkPMColor,
 // but as a float in the range [0, 255].
 class SK_STRUCT_ALIGN(16) SkPMFloat {
 public:
     static SkPMFloat FromPMColor(SkPMColor c) { return SkPMFloat(c); }
     static SkPMFloat FromARGB(float a, float r, float g, float b) { return SkPMFloat(a,r,g,b); }
 
@@ skipping 37 matching lines @@
             && this->r() >= 0 && this->r() <= this->a()
             && this->g() >= 0 && this->g() <= this->a()
             && this->b() >= 0 && this->b() <= this->a();
     }
 
 private:
     union {
         float fColor[4];
 #if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
         __m128 fColors;
-#elif defined(__ARM_NEON__)
+#elif defined(SK_ARM_HAS_NEON)
         float32x4_t fColors;
 #endif
     };
 };
 
 #if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSSE3
     #include "../opts/SkPMFloat_SSSE3.h"
 #elif SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
     #include "../opts/SkPMFloat_SSE2.h"
-#elif defined(__ARM_NEON__)
+#elif defined(SK_ARM_HAS_NEON)
     #include "../opts/SkPMFloat_neon.h"
 #else
     #include "../opts/SkPMFloat_none.h"
 #endif
 
 #endif//SkPM_DEFINED