db/upnp/Discovery: un-inline the destructor

src/db/upnp/Discovery.cxx

@@ -192,6 +192,11 @@ UPnPDeviceDirectory::UPnPDeviceDirectory(LibUPnP *_lib)
 {
 }
 
+UPnPDeviceDirectory::~UPnPDeviceDirectory()
+{
+	/* this destructor exists here just so it won't get inlined */
+}
+
 bool
 UPnPDeviceDirectory::Start(Error &error)
 {

src/db/upnp/Discovery.hxx

@@ -102,6 +102,7 @@ class UPnPDeviceDirectory {
 
 public:
 	UPnPDeviceDirectory(LibUPnP *_lib);
+	~UPnPDeviceDirectory();
 
 	UPnPDeviceDirectory(const UPnPDeviceDirectory &) = delete;
 	UPnPDeviceDirectory& operator=(const UPnPDeviceDirectory &) = delete;