Upgrade Embree to the latest official release.

Since Embree v3.13.0 supports AARCH64, switch back to the
official repo instead of using Embree-aarch64.

`thirdparty/embree/patches/godot-changes.patch` should now contain
an accurate diff of the changes done to the library.

thirdparty/embree/common/algorithms/parallel_set.h

@@ -0,0 +1,52 @@
+// Copyright 2009-2021 Intel Corporation
+// SPDX-License-Identifier: Apache-2.0
+
+#pragma once
+
+#include "parallel_sort.h"
+
+namespace embree
+{
+  /* implementation of a set of values with parallel construction */
+  template<typename T>
+  class parallel_set
+  {
+  public:
+
+    /*! default constructor for the parallel set */
+    parallel_set () {}
+
+    /*! construction from vector */
+    template<typename Vector>
+      parallel_set (const Vector& in) { init(in); }
+
+    /*! initialized the parallel set from a vector */
+    template<typename Vector>
+      void init(const Vector& in) 
+    {
+      /* copy data to internal vector */
+      vec.resize(in.size());
+      parallel_for( size_t(0), in.size(), size_t(4*4096), [&](const range<size_t>& r) {
+	for (size_t i=r.begin(); i<r.end(); i++) 
+	  vec[i] = in[i];
+      });
+
+      /* sort the data */
+      std::vector<T> temp(in.size());
+      radix_sort<T>(vec.data(),temp.data(),vec.size());
+    }
+
+    /*! tests if some element is in the set */
+    __forceinline bool lookup(const T& elt) const {
+      return std::binary_search(vec.begin(), vec.end(), elt);
+    }
+
+    /*! clears all state */
+    void clear() {
+      vec.clear();
+    }
+
+  private:
+    std::vector<T> vec;   //!< vector containing sorted elements
+  };
+}