Directory: add constructor and destructor

test/DumpPlaylist.cxx

@@ -20,6 +20,7 @@
 #include "config.h"
 #include "TagSave.hxx"
 #include "song.h"
+#include "Directory.hxx"
 
 extern "C" {
 #include "io_thread.h"
@@ -37,6 +38,8 @@ extern "C" {
 #include <unistd.h>
 #include <stdlib.h>
 
+Directory::~Directory() {}
+
 static void
 my_log_func(const gchar *log_domain, G_GNUC_UNUSED GLogLevelFlags log_level,
 	    const gchar *message, G_GNUC_UNUSED gpointer user_data)

test/TestQueuePriority.cxx

@@ -7,6 +7,8 @@ extern "C" {
 
 Directory detached_root;
 
+Directory::~Directory() {}
+
 struct song *
 song_dup_detached(const struct song *src)
 {