build: Fixing and suppressing all warnings

clang generates a number of harmless warnings originated from cryptopp
library.

Change-Id: I676e7b6d60588867f55a2ce1cd88ef263c3e38df
diff --git a/include/ndn-cpp/security/key-chain.hpp b/include/ndn-cpp/security/key-chain.hpp
index 29bd164..6d1e212 100644
--- a/include/ndn-cpp/security/key-chain.hpp
+++ b/include/ndn-cpp/security/key-chain.hpp
@@ -172,7 +172,7 @@
 
   ptr_lib::shared_ptr<Face>        face_;
   
-  const int maxSteps_;
+  // const int maxSteps_;
 };
 
 void