Fix -Wextra-semi warnings.

Starting from https://chromium-review.googlesource.com/c/1485012,
-Wextra-semi is enabled and WebRTC has some violations to fix.

This is a follow-up of https://webrtc-review.googlesource.com/c/123560.

Bug: webrtc:10355
Change-Id: I012b7497fc8991037fd77aa98f1579c22e08206f
Reviewed-on: https://webrtc-review.googlesource.com/c/124126
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26831}

modules/audio_processing/audio_processing_impl_unittest.cc

@@ -133,7 +133,7 @@ class TestRenderPreProcessor : public CustomProcessing {
       std::transform(channel_view.begin(), channel_view.end(),
                      channel_view.begin(), ProcessSample);
     }
-  };
+  }
   std::string ToString() const override { return "TestRenderPreProcessor"; }
   void SetRuntimeSetting(AudioProcessing::RuntimeSetting setting) override {}
   // Modifies a sample. This member is used in Process() to modify a frame and