Guard SIMD code with !defined(SKNX_NO_SIMD).

src/core/Sk2x.h

Index: src/core/Sk2x.h
diff --git a/src/core/Sk2x.h b/src/core/Sk2x.h
index 5e78c503d5aa5c0cd88e7408dca3252dea68defa..910476efd7ea75dfbdc1d8a136fcc8dc55b75cad 100644
--- a/src/core/Sk2x.h
+++ b/src/core/Sk2x.h
@@ -9,11 +9,12 @@
 #define Sk2x_DEFINED
 
 #include "SkTypes.h"
+#include "SkNx.h"
 
 #define SK2X_PREAMBLE 1
-    #if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
+    #if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2 && !defined(SKNX_NO_SIMD)
         #include "../opts/Sk2x_sse.h"
-    #elif defined(__ARM_NEON__)
+    #elif defined(__ARM_NEON__)                   && !defined(SKNX_NO_SIMD)
         #include "../opts/Sk2x_neon.h"
     #else
         #include "../opts/Sk2x_none.h"
@@ -65,9 +66,9 @@ public:
 
 private:
 #define SK2X_PRIVATE 1
-    #if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
+    #if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2 && !defined(SKNX_NO_SIMD)
         #include "../opts/Sk2x_sse.h"
-    #elif defined(__ARM_NEON__)
+    #elif defined(__ARM_NEON__)                   && !defined(SKNX_NO_SIMD)
         #include "../opts/Sk2x_neon.h"
     #else
         #include "../opts/Sk2x_none.h"
@@ -75,9 +76,9 @@ private:
 #undef SK2X_PRIVATE
 };
 
-#if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
+#if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2 && !defined(SKNX_NO_SIMD)
     #include "../opts/Sk2x_sse.h"
-#elif defined(__ARM_NEON__)
+#elif defined(__ARM_NEON__)                   && !defined(SKNX_NO_SIMD)
     #include "../opts/Sk2x_neon.h"
 #else
     #include "../opts/Sk2x_none.h"