[gnome-panel] force-quit: fix -Wsign-compare warning

[Alberts Muktupāvels <muktupavels src gnome org>]

commit 2bef24459fdd9ee8d5c321f156b056454ad68702
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Sun Mar 8 00:48:31 2020 +0200

    force-quit: fix -Wsign-compare warning

 gnome-panel/panel-force-quit.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/gnome-panel/panel-force-quit.c b/gnome-panel/panel-force-quit.c
index 762145e65..7eb1fc620 100644
--- a/gnome-panel/panel-force-quit.c
+++ b/gnome-panel/panel-force-quit.c
@@ -159,7 +159,8 @@ find_managed_window (Display *display,
        Window *kids = NULL;
        Window  retval;
        guint   nkids;
-       int     i, result;
+       guint   i;
+       int     result;
 
        if (wm_state_set (display, window))
                return window;