made audiorenderingparams == operators const

There's no reason these functions shouldn't be const and we need to access it
in situations where instances of this class are const.

app/render/audioparams.cpp

@@ -48,14 +48,14 @@ const SampleFormat &AudioRenderingParams::format() const
   return format_;
 }
 
-bool AudioRenderingParams::operator==(const AudioRenderingParams &other)
+bool AudioRenderingParams::operator==(const AudioRenderingParams &other) const
 {
   return (format() == other.format()
           && sample_rate() == other.sample_rate()
           && channel_layout() == other.channel_layout());
 }
 
-bool AudioRenderingParams::operator!=(const AudioRenderingParams &other)
+bool AudioRenderingParams::operator!=(const AudioRenderingParams &other) const
 {
   return (format() != other.format()
           || sample_rate() != other.sample_rate()

app/render/audioparams.h

@@ -39,8 +39,8 @@ public:
 
   const SampleFormat& format() const;
 
-  bool operator==(const AudioRenderingParams& other);
-  bool operator!=(const AudioRenderingParams& other);
+  bool operator==(const AudioRenderingParams& other) const;
+  bool operator!=(const AudioRenderingParams& other) const;
 
 private:
   SampleFormat format_;