GN: Fix test_support_unittests and MIPS compile issue.

webrtc/system_wrappers/include/logcat_trace_context.h

Index: webrtc/system_wrappers/include/logcat_trace_context.h
diff --git a/webrtc/system_wrappers/include/logcat_trace_context.h b/webrtc/system_wrappers/include/logcat_trace_context.h
index 8bb01d8102c94d8e5a52e0ad84bd96850e5cc08d..fc36386c709740703caa00c39a7ce4401d68c1bd 100644
--- a/webrtc/system_wrappers/include/logcat_trace_context.h
+++ b/webrtc/system_wrappers/include/logcat_trace_context.h
@@ -24,10 +24,10 @@ namespace webrtc {
 class LogcatTraceContext : public webrtc::TraceCallback {
  public:
   LogcatTraceContext();
-  virtual ~LogcatTraceContext();
+  ~LogcatTraceContext() override;
 
   // TraceCallback impl.
-  virtual void Print(TraceLevel level, const char* message, int length);
+  void Print(TraceLevel level, const char* message, int length) override;
 };
 
 }  // namespace webrtc