Fix GCC 4.7 errors

GCC 4.7.2 fail overriding constructors defined with virtual and default.
Debian build also fails linking  without -lrt.
INT64_C is not defined on Debian with 4.7.2. "ll" should be enough.

Change-Id: Ia779f094ed64fc3b1941429485e81520d017c2f5
Reviewed-on: https://weave-review.googlesource.com/1671
Reviewed-by: Alex Vakulenko <avakulenko@google.com>
diff --git a/src/privet/security_delegate.h b/src/privet/security_delegate.h
index 1d28ba3..40f297f 100644
--- a/src/privet/security_delegate.h
+++ b/src/privet/security_delegate.h
@@ -19,7 +19,7 @@
 // Interface to provide Security related logic for |PrivetHandler|.
 class SecurityDelegate {
  public:
-  virtual ~SecurityDelegate() = default;
+  virtual ~SecurityDelegate() {}
 
   // Creates access token for the given scope, user id and |time|.
   virtual std::string CreateAccessToken(const UserInfo& user_info,