AEC3: avoiding a warning in the reverberation decay estimator.

In this CL a warning is avoided in the reverberation decay estimator code. The change is bitexact.

Bug: chromium:921582
Change-Id: I5a91f4b5970a21ba6da7254cf7fad8c2d0bcac4b
Reviewed-on: https://webrtc-review.googlesource.com/c/118441
Commit-Queue: Jesus de Vicente Pena <devicentepena@webrtc.org>
Reviewed-by: Per Åhgren <peah@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26342}

modules/audio_processing/aec3/reverb_decay_estimator.cc

diff --git a/modules/audio_processing/aec3/reverb_decay_estimator.cc b/modules/audio_processing/aec3/reverb_decay_estimator.cc
index 95fd13a..b0082f1 100644
--- a/modules/audio_processing/aec3/reverb_decay_estimator.cc
+++ b/modules/audio_processing/aec3/reverb_decay_estimator.cc
@@ -287,7 +287,7 @@
   // Arithmetic sum of $2 \sum_{i=0.5}^{(N-1)/2}i^2$ calculated directly.
   nn_ = SymmetricArithmetricSum(N);
   // The linear regression approach assumes symmetric index around 0.
-  count_ = N > 0 ? count_ = -N * 0.5f + 0.5f : 0.f;
+  count_ = N > 0 ? -N * 0.5f + 0.5f : 0.f;
   N_ = N;
   n_ = 0;
 }