Update to current webrtc library

This is from the upstream library commit id
3326535126e435f1ba647885ce43a8f0f3d317eb, corresponding to Chromium
88.0.4290.1.

webrtc/modules/audio_processing/ns/fast_math.h

@@ -0,0 +1,38 @@
+/*
+ *  Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef MODULES_AUDIO_PROCESSING_NS_FAST_MATH_H_
+#define MODULES_AUDIO_PROCESSING_NS_FAST_MATH_H_
+
+#include "api/array_view.h"
+
+namespace webrtc {
+
+// Sqrt approximation.
+float SqrtFastApproximation(float f);
+
+// Log base conversion log(x) = log2(x)/log2(e).
+float LogApproximation(float x);
+void LogApproximation(rtc::ArrayView<const float> x, rtc::ArrayView<float> y);
+
+// 2^x approximation.
+float Pow2Approximation(float p);
+
+// x^p approximation.
+float PowApproximation(float x, float p);
+
+// e^x approximation.
+float ExpApproximation(float x);
+void ExpApproximation(rtc::ArrayView<const float> x, rtc::ArrayView<float> y);
+void ExpApproximationSignFlip(rtc::ArrayView<const float> x,
+                              rtc::ArrayView<float> y);
+}  // namespace webrtc
+
+#endif  // MODULES_AUDIO_PROCESSING_NS_FAST_MATH_H_