security: Hiding sqlite3 from the header of SecPublicInfoSqlite

Change-Id: Ic45d06b013bbe8f96f9472a6f8b95d02820437f5
diff --git a/include/ndn-cpp-dev/security/sec-public-info-sqlite3.hpp b/include/ndn-cpp-dev/security/sec-public-info-sqlite3.hpp
index f83c27e..8468fc2 100644
--- a/include/ndn-cpp-dev/security/sec-public-info-sqlite3.hpp
+++ b/include/ndn-cpp-dev/security/sec-public-info-sqlite3.hpp
@@ -13,10 +13,11 @@
 #include <ndn-cpp-dev/ndn-cpp-config.h>
 #ifdef NDN_CPP_HAVE_SQLITE3
 
-#include <sqlite3.h>
 #include "../common.hpp"
 #include "sec-public-info.hpp"
 
+struct sqlite3;
+
 namespace ndn
 {