patch 8.2.2622: GTK: error when starting up and -geometry is given

Problem:    GTK: error when starting up and -geometry is given. (Dominique
            Pellé)
Solution:   Use another function to get the monitor if the window has not been
            created yet. (closes #7978)
diff --git a/src/proto/gui_gtk_x11.pro b/src/proto/gui_gtk_x11.pro
index 3f26044..1d0a78b 100644
--- a/src/proto/gui_gtk_x11.pro
+++ b/src/proto/gui_gtk_x11.pro
@@ -18,6 +18,8 @@
 int gui_mch_init(void);
 void gui_mch_forked(void);
 void gui_mch_new_colors(void);
+void gui_gtk_get_screen_geom_of_win(GtkWidget *wid, int point_x, int point_y, int *screen_x, int *screen_y, int *width, int *height);
+void gui_mch_get_screen_dimensions(int *screen_w, int *screen_h);
 int gui_mch_open(void);
 void gui_mch_exit(int rc);
 int gui_mch_get_winpos(int *x, int *y);
@@ -26,8 +28,6 @@
 void gui_mch_unmaximize(void);
 void gui_mch_newfont(void);
 void gui_mch_set_shellsize(int width, int height, int min_width, int min_height, int base_width, int base_height, int direction);
-void gui_gtk_get_screen_geom_of_win(GtkWidget *wid, int *screen_x, int *screen_y, int *width, int *height);
-void gui_mch_get_screen_dimensions(int *screen_w, int *screen_h);
 void gui_mch_settitle(char_u *title, char_u *icon);
 void gui_mch_enable_menu(int showit);
 void gui_mch_show_toolbar(int showit);