build: Fixing and suppressing all warnings

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

Change-Id: I676e7b6d60588867f55a2ce1cd88ef263c3e38df
diff --git a/src/security/certificate/certificate-subject-description.cpp b/src/security/certificate/certificate-subject-description.cpp
index 472b30e..c91cb6a 100644
--- a/src/security/certificate/certificate-subject-description.cpp
+++ b/src/security/certificate/certificate-subject-description.cpp
@@ -6,6 +6,19 @@
  * See COPYING for copyright and distribution information.
  */
 
+#if __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wreorder"
+#pragma clang diagnostic ignored "-Wtautological-compare"
+#pragma clang diagnostic ignored "-Wunused-variable"
+#pragma clang diagnostic ignored "-Wunused-function"
+#elif __GNUC__
+#pragma GCC diagnostic ignored "-Wreorder"
+#pragma GCC diagnostic ignored "-Wtautological-compare"
+#pragma GCC diagnostic ignored "-Wunused-variable"
+#pragma GCC diagnostic ignored "-Wunused-function"
+#endif
+
 #include <ndn-cpp/security/certificate/certificate-subject-description.hpp>
 #include <cryptopp/asn.h>