Convert IntelligibilityEnhancer to multi-threaded mode

webrtc/modules/audio_processing/noise_suppression_impl.cc

Index: webrtc/modules/audio_processing/noise_suppression_impl.cc
diff --git a/webrtc/modules/audio_processing/noise_suppression_impl.cc b/webrtc/modules/audio_processing/noise_suppression_impl.cc
index 7f19005924de76373ebe8547337e341ad0656767..a9d9f4a93bbf8086105ea4cb28fc0ee181be644b 100644
--- a/webrtc/modules/audio_processing/noise_suppression_impl.cc
+++ b/webrtc/modules/audio_processing/noise_suppression_impl.cc
@@ -200,4 +200,12 @@ std::vector<float> NoiseSuppressionImpl::NoiseEstimate() {
   return noise_estimate;
 }
 
+size_t NoiseSuppressionImpl::num_noise_bins() {
+#if defined(WEBRTC_NS_FLOAT)
+  return WebRtcNs_num_freq();
+#elif defined(WEBRTC_NS_FIXED)
+  return WebRtcNsx_num_freq();
+#endif
+}
+
 }  // namespace webrtc