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/include/embree3/rtcore_buffer.h

@@ -0,0 +1,51 @@
+// Copyright 2009-2021 Intel Corporation
+// SPDX-License-Identifier: Apache-2.0
+
+#pragma once
+
+#include "rtcore_device.h"
+
+RTC_NAMESPACE_BEGIN
+
+/* Types of buffers */
+enum RTCBufferType
+{
+  RTC_BUFFER_TYPE_INDEX            = 0,
+  RTC_BUFFER_TYPE_VERTEX           = 1,
+  RTC_BUFFER_TYPE_VERTEX_ATTRIBUTE = 2,
+  RTC_BUFFER_TYPE_NORMAL           = 3,
+  RTC_BUFFER_TYPE_TANGENT          = 4,
+  RTC_BUFFER_TYPE_NORMAL_DERIVATIVE = 5,
+
+  RTC_BUFFER_TYPE_GRID                 = 8,
+
+  RTC_BUFFER_TYPE_FACE                 = 16,
+  RTC_BUFFER_TYPE_LEVEL                = 17,
+  RTC_BUFFER_TYPE_EDGE_CREASE_INDEX    = 18,
+  RTC_BUFFER_TYPE_EDGE_CREASE_WEIGHT   = 19,
+  RTC_BUFFER_TYPE_VERTEX_CREASE_INDEX  = 20,
+  RTC_BUFFER_TYPE_VERTEX_CREASE_WEIGHT = 21,
+  RTC_BUFFER_TYPE_HOLE                 = 22,
+
+  RTC_BUFFER_TYPE_FLAGS = 32
+};
+
+/* Opaque buffer type */
+typedef struct RTCBufferTy* RTCBuffer;
+
+/* Creates a new buffer. */
+RTC_API RTCBuffer rtcNewBuffer(RTCDevice device, size_t byteSize);
+
+/* Creates a new shared buffer. */
+RTC_API RTCBuffer rtcNewSharedBuffer(RTCDevice device, void* ptr, size_t byteSize);
+
+/* Returns a pointer to the buffer data. */
+RTC_API void* rtcGetBufferData(RTCBuffer buffer);
+
+/* Retains the buffer (increments the reference count). */
+RTC_API void rtcRetainBuffer(RTCBuffer buffer);
+
+/* Releases the buffer (decrements the reference count). */
+RTC_API void rtcReleaseBuffer(RTCBuffer buffer);
+
+RTC_NAMESPACE_END