AGC2: max adaptation speed now part of config

Tested: bit-exactness verified with audioproc_f

Bug: webrtc:7494
Change-Id: Ie65a2e2139cff0bd730307d06b74760e307c9568
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/186264
Commit-Queue: Alessio Bazzica <alessiob@webrtc.org>
Reviewed-by: Minyue Li <minyue@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#32277}
diff --git a/modules/audio_processing/include/audio_processing.h b/modules/audio_processing/include/audio_processing.h
index e96a45b..a56b315 100644
--- a/modules/audio_processing/include/audio_processing.h
+++ b/modules/audio_processing/include/audio_processing.h
@@ -353,6 +353,7 @@
         float initial_saturation_margin_db = 20.f;
         float extra_saturation_margin_db = 2.f;
         int gain_applier_adjacent_speech_frames_threshold = 1;
+        float max_gain_change_db_per_second = 3.f;
       } adaptive_digital;
     } gain_controller2;