Add AudioOption for residual echo detector, and enable it by default on non-mobile platforms.

webrtc/modules/audio_processing/include/audio_processing.h

Index: webrtc/modules/audio_processing/include/audio_processing.h
diff --git a/webrtc/modules/audio_processing/include/audio_processing.h b/webrtc/modules/audio_processing/include/audio_processing.h
index 3225a4cdbb282cbd0fff95fd76c301875b07e08b..71ba5ff370ced10f3bc63ffa3b70c2cd1eafac84 100644
--- a/webrtc/modules/audio_processing/include/audio_processing.h
+++ b/webrtc/modules/audio_processing/include/audio_processing.h
@@ -259,7 +259,11 @@ class AudioProcessing {
       float initial_peak_level_dbfs = -6.0206f;
     } level_controller;
     struct ResidualEchoDetector {
+#if defined(WEBRTC_ANDROID) || defined(WEBRTC_IOS)
       bool enabled = false;
+#else
+      bool enabled = true;
+#endif
     } residual_echo_detector;
   };