[gtk/gtk-3-22] gdk_x11_display_get_monitor: fix monitor number test logic

[Daniel Boles <dboles src gnome org>]

commit 59136773b87f7d93ad11d37edd932d68d67b3fff
Author: Sébastien Villemot <sebastien debian org>
Date:   Mon Apr 9 15:36:36 2018 +0200

    gdk_x11_display_get_monitor: fix monitor number test logic
    
    When asked for a nonexistent (positive) monitor number,
    gdk_x11_display_get_monitor would (at best) return an uninitialized pointer,
    instead of returning NULL.
    
    https://gitlab.gnome.org/GNOME/gtk/merge_requests/107

 gdk/x11/gdkdisplay-x11.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/gdk/x11/gdkdisplay-x11.c b/gdk/x11/gdkdisplay-x11.c
index 75bd34c2cd..46421cbf41 100644
--- a/gdk/x11/gdkdisplay-x11.c
+++ b/gdk/x11/gdkdisplay-x11.c
@@ -3122,7 +3122,7 @@ gdk_x11_display_get_monitor (GdkDisplay *display,
 {
   GdkX11Display *x11_display = GDK_X11_DISPLAY (display);
 
-  if (0 <= monitor_num || monitor_num < x11_display->monitors->len)
+  if (0 <= monitor_num && monitor_num < x11_display->monitors->len)
     return (GdkMonitor *)x11_display->monitors->pdata[monitor_num];
 
   return NULL;