shill: Add C++11 override specifier to destructors of derived classes.

BUG=None
TEST=`USE=wimax FEATURES=test emerge-$BOARD platform2`

Change-Id: I88d4e29165869b26924cccb94ac940dc8961c312
Reviewed-on: https://chromium-review.googlesource.com/212267
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Commit-Queue: Ben Chan <benchan@chromium.org>
Tested-by: Ben Chan <benchan@chromium.org>
diff --git a/mock_socket_info_reader.h b/mock_socket_info_reader.h
index 1ced570..eae003c 100644
--- a/mock_socket_info_reader.h
+++ b/mock_socket_info_reader.h
@@ -19,7 +19,7 @@
 class MockSocketInfoReader : public SocketInfoReader {
  public:
   MockSocketInfoReader();
-  virtual ~MockSocketInfoReader();
+  ~MockSocketInfoReader() override;
 
   MOCK_METHOD1(LoadTcpSocketInfo, bool(std::vector<SocketInfo> *info_list));