tools: Fix bugs in cert-gen

Change-Id: I13ed1d71b4970166135e32e2196ac9c67ad60fd3
Refs: #4202
diff --git a/src/security/v2/additional-description.hpp b/src/security/v2/additional-description.hpp
index ad9df37..5e16132 100644
--- a/src/security/v2/additional-description.hpp
+++ b/src/security/v2/additional-description.hpp
@@ -78,6 +78,12 @@
     return m_info.size();
   }
 
+  bool
+  empty() const
+  {
+    return m_info.empty();
+  }
+
   iterator
   begin();