Update audio code to use size_t more correctly,

webrtc/common_audio/signal_processing/complex_fft.c

 /*
  *  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.
  */
 
@@ skipping 139 matching lines @@
 
             --k;
             l = istep;
         }
     }
     return 0;
 }
 
 int WebRtcSpl_ComplexIFFT(int16_t frfi[], int stages, int mode)
 {
-    int i, j, l, k, istep, n, m, scale, shift;
+    size_t i, j, l, istep, n, m;
+    int k, scale, shift;
     int16_t wr, wi;
     int32_t tr32, ti32, qr32, qi32;
     int32_t tmp32, round2;
 
     /* The 1024-value is a constant given from the size of kSinTable1024[],
      * and should not be changed depending on the input parameter 'stages'
      */
     n = 1 << stages;
     if (n > 1024)
         return -1;
@@ skipping 117 matching lines @@
                         (qi32 + ti32 + round2) >> (shift + CIFFTSFT));
                 }
             }
 
         }
         --k;
         l = istep;
     }
     return scale;
 }