neon implementation

removed some x86 intrinsic functions that were in the mat44_impl file
reinstated some mMath_C functions and mMathFn ptrs trying to diagnose an issue.
Had to come up with a different way to initialize the scalar table if the isa tables are not initialized yet. Mac did not like the static initialization.
Had to change neon over to using explicit masks for shifting, cross product was failing during bakes and matrix calculations

Engine/source/math/public/math_backend.h

@@ -35,4 +35,61 @@ namespace math_backend
    void install_from_cpu_flags(uint32_t cpu_flags);
 }
 
+#include <mutex>
+
+namespace math_backend::float4::dispatch
+{
+   //--------------------------------------------------
+   // Thread-safe getter, ensures scalar installed if empty
+   //--------------------------------------------------
+   inline Float4Funcs& GetFloat4()
+   {
+      if (__builtin_expect(gFloat4.mul == nullptr, 0))
+      {
+         static std::once_flag once;
+         std::call_once(once, []{
+            install_scalar();
+         });
+      }
+      return gFloat4;
+   }
+}
+
+namespace math_backend::float3::dispatch
+{
+   //--------------------------------------------------
+   // Thread-safe getter, ensures scalar installed if empty
+   //--------------------------------------------------
+   inline Float3Funcs& GetFloat3()
+   {
+      if (__builtin_expect(gFloat3.mul == nullptr, 0))
+      {
+         static std::once_flag once;
+         std::call_once(once, []{
+            install_scalar();
+         });
+      }
+      return gFloat3;
+   }
+}
+
+
+namespace math_backend::mat44::dispatch
+{
+   //--------------------------------------------------
+   // Thread-safe getter, ensures scalar installed if empty
+   //--------------------------------------------------
+   inline Mat44Funcs& GetMat44()
+   {
+      if (__builtin_expect(gMat44.mul_mat44 == nullptr, 0))
+      {
+         static std::once_flag once;
+         std::call_once(once, []{
+            install_scalar();
+         });
+      }
+      return gMat44;
+   }
+}
+
 #endif // !_MATH_BACKEND_H_