xfce4-settings error

Build Configuration:

* Installation prefix:       /usr/local
* Debug Support:             full
* gtk3 Support:              yes
* Xrandr support:            yes
* UPower support:            yes
* Libnotify support:         yes
* Xcursor support:           yes
* Embedded settings dialogs  no
* Sounds settings support    no
* Libxklavier support:       yes
* Mime settings (gio-unix):  yes
* Datetime settings support: yes

Now type "make" to compile.
edoardo@silenzio ~/Project/Developement/Xfce/xfce4-settings $ make
make  all-recursive
make[1]: Entering directory `/home/edoardo/Project/Developement/Xfce/xfce4-settings'
Making all in dialogs
make[2]: Entering directory `/home/edoardo/Project/Developement/Xfce/xfce4-settings/dialogs'
Making all in appearance-settings
make[3]: Entering directory `/home/edoardo/Project/Developement/Xfce/xfce4-settings/dialogs/appearance-settings'
exo-csource --static --strip-comments --strip-content --name=appearance_dialog_ui appearance-dialog.glade >appearance-dialog_ui.h
make  all-am
make[4]: Entering directory `/home/edoardo/Project/Developement/Xfce/xfce4-settings/dialogs/appearance-settings'
  CC       xfce4_appearance_settings-main.o
In file included from /usr/include/stdlib.h:24:0,
                 from main.c:25:
/usr/include/features.h:327:4: error: #warning _FORTIFY_SOURCE requires compiling with optimization (-O) [-Werror=cpp]
 #  warning _FORTIFY_SOURCE requires compiling with optimization (-O)
    ^
main.c:91:1: error: unknown type name ‘GdkNativeWindow’
 static GdkNativeWindow opt_socket_id = 0;
 ^
main.c: In function ‘cb_custom_dpi_spin_button_changed’:
main.c:256:5: error: implicit declaration of function ‘GTK_WIDGET_IS_SENSITIVE’ [-Werror=implicit-function-declaration]
     if (GTK_WIDGET_IS_SENSITIVE (custom_dpi_spin) && gtk_toggle_button_get_active (custom_dpi_toggle))
     ^
main.c:256:5: error: nested extern declaration of ‘GTK_WIDGET_IS_SENSITIVE’ [-Werror=nested-externs]
main.c: In function ‘cb_theme_uri_dropped’:
main.c:805:5: error: ‘gdk_cursor_unref’ is deprecated (declared at /usr/include/gtk-3.0/gdk/gdkcursor.h:233): Use 'g_object_unref' instead [-Werror=deprecated-declarations]
     gdk_cursor_unref (cursor);
     ^
main.c: In function ‘main’:
main.c:1071:17: error: implicit declaration of function ‘gdk_set_sm_client_id’ [-Werror=implicit-function-declaration]
                 gdk_set_sm_client_id ("FAKE ID");
                 ^
main.c:1071:17: error: nested extern declaration of ‘gdk_set_sm_client_id’ [-Werror=nested-externs]
main.c:1078:17: error: implicit declaration of function ‘gtk_plug_new’ [-Werror=implicit-function-declaration]
                 plug = gtk_plug_new (opt_socket_id);
                 ^
main.c:1078:17: error: nested extern declaration of ‘gtk_plug_new’ [-Werror=nested-externs]
main.c:1078:22: error: assignment makes pointer from integer without a cast [-Werror]
                 plug = gtk_plug_new (opt_socket_id);
                      ^
cc1: all warnings being treated as errors
make[4]: *** [xfce4_appearance_settings-main.o] Errore 1
make[4]: Leaving directory `/home/edoardo/Project/Developement/Xfce/xfce4-settings/dialogs/appearance-settings'
make[3]: *** [all] Errore 2
make[3]: Leaving directory `/home/edoardo/Project/Developement/Xfce/xfce4-settings/dialogs/appearance-settings'
make[2]: *** [all-recursive] Errore 1
make[2]: Leaving directory `/home/edoardo/Project/Developement/Xfce/xfce4-settings/dialogs'
make[1]: *** [all-recursive] Errore 1
make[1]: Leaving directory `/home/edoardo/Project/Developement/Xfce/xfce4-settings'
make: *** [all] Errore 2
edoardo@silenzio ~/Project/Developement/Xfce/xfce4-settings $