Added a query function for whether submodules are enabled

that can be called from the render side without making APM
singlethreaded.

This CL is addressing the problems with high render-side
call duration that were triggered by the CL
https://codereview.webrtc.org/1844583003

BUG=webrtc:5736

Review URL: https://codereview.webrtc.org/1859243002

Cr-Commit-Position: refs/heads/master@{#12266}

webrtc/modules/audio_processing/gain_control_impl.h

@@ -43,6 +43,11 @@ class GainControlImpl : public GainControl {
   bool is_limiter_enabled() const override;
   Mode mode() const override;
 
+  // Checks whether the module is enabled. Must only be
+  // called from the render side of APM as otherwise
+  // deadlocks may occur.
+  bool is_enabled_render_side_query() const;
+
   // Reads render side data that has been queued on the render call.
   void ReadQueuedRenderData();