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_eap_credentials.h b/mock_eap_credentials.h
index 5ba09bc..97b604e 100644
--- a/mock_eap_credentials.h
+++ b/mock_eap_credentials.h
@@ -18,7 +18,7 @@
 class MockEapCredentials : public EapCredentials {
  public:
   MockEapCredentials();
-  virtual ~MockEapCredentials();
+  ~MockEapCredentials() override;
 
   MOCK_CONST_METHOD0(IsConnectable, bool());
   MOCK_CONST_METHOD0(IsConnectableUsingPassphrase, bool());