Change default database path and configuration directory

Now respectively ${LOCALSTATEDIR}/lib/ndn/ndns/ndns.db
and ${SYSCONFDIR}/ndn/ndns

Refs: #4810
Change-Id: I351a6a15f8daa0a032845cb26d5d76179faa7b27
diff --git a/src/daemon/db-mgr.cpp b/src/daemon/db-mgr.cpp
index ef5f23c..da40d58 100644
--- a/src/daemon/db-mgr.cpp
+++ b/src/daemon/db-mgr.cpp
@@ -20,6 +20,7 @@
 #include "db-mgr.hpp"
 #include "logger.hpp"
 #include "clients/response.hpp"
+#include "util/util.hpp"
 
 namespace ndn {
 namespace ndns {
@@ -53,12 +54,12 @@
   ON rrsets (zone_id, label, type, version);
 )VALUE";
 
-DbMgr::DbMgr(const std::string& dbFile/* = DEFAULT_CONFIG_PATH "/" "ndns.db"*/)
+DbMgr::DbMgr(const std::string& dbFile)
   : m_dbFile(dbFile)
   , m_conn(nullptr)
 {
-  if (dbFile.empty())
-    m_dbFile = DEFAULT_DATABASE_PATH "/" "ndns.db";
+  if (m_dbFile.empty())
+    m_dbFile = getDefaultDatabaseFile();
 
   open();
 
diff --git a/src/daemon/db-mgr.hpp b/src/daemon/db-mgr.hpp
index c21b3e0..a41380a 100644
--- a/src/daemon/db-mgr.hpp
+++ b/src/daemon/db-mgr.hpp
@@ -65,7 +65,7 @@
 
 public:
   explicit
-  DbMgr(const std::string& dbFile = DEFAULT_DATABASE_PATH "/" "ndns.db");
+  DbMgr(const std::string& dbFile = "");
 
   ~DbMgr();