Update to current webrtc library

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

webrtc/modules/third_party/fft/fft.h

@@ -0,0 +1,58 @@
+/*
+ *  Copyright (c) 2011 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.
+ */
+
+/*--------------------------------*-C-*---------------------------------*
+ * File:
+ *       fftn.h
+ * ---------------------------------------------------------------------*
+ * Re[]:        real value array
+ * Im[]:        imaginary value array
+ * nTotal:      total number of complex values
+ * nPass:       number of elements involved in this pass of transform
+ * nSpan:       nspan/nPass = number of bytes to increment pointer
+ *              in Re[] and Im[]
+ * isign: exponent: +1 = forward  -1 = reverse
+ * scaling: normalizing constant by which the final result is *divided*
+ * scaling == -1, normalize by total dimension of the transform
+ * scaling <  -1, normalize by the square-root of the total dimension
+ *
+ * ----------------------------------------------------------------------
+ * See the comments in the code for correct usage!
+ */
+
+#ifndef MODULES_THIRD_PARTY_FFT_FFT_H_
+#define MODULES_THIRD_PARTY_FFT_FFT_H_
+
+#define FFT_MAXFFTSIZE 2048
+#define FFT_NFACTOR 11
+
+typedef struct {
+  unsigned int SpaceAlloced;
+  unsigned int MaxPermAlloced;
+  double Tmp0[FFT_MAXFFTSIZE];
+  double Tmp1[FFT_MAXFFTSIZE];
+  double Tmp2[FFT_MAXFFTSIZE];
+  double Tmp3[FFT_MAXFFTSIZE];
+  int Perm[FFT_MAXFFTSIZE];
+  int factor[FFT_NFACTOR];
+
+} FFTstr;
+
+/* double precision routine */
+
+int WebRtcIsac_Fftns(unsigned int ndim,
+                     const int dims[],
+                     double Re[],
+                     double Im[],
+                     int isign,
+                     double scaling,
+                     FFTstr* fftstate);
+
+#endif /* MODULES_THIRD_PARTY_FFT_FFT_H_ */