Swapping around vec128 to match AVX order.

Was really hoping all this would fix some bugs, but no luck :(

src/poly/math.h

@@ -12,6 +12,7 @@
 
 #include <xmmintrin.h>
 
+#include <algorithm>
 #include <cstdint>
 #include <cstring>
 #include <type_traits>
@@ -38,6 +39,10 @@ T round_up(T value, V multiple) {
   return value + multiple - 1 - (value - 1) % multiple;
 }
 
+inline float saturate(float value) {
+  return std::max(std::min(1.0f, value), -1.0f);
+}
+
 // Gets the next power of two value that is greater than or equal to the given
 // value.
 template <typename T>