[gtk/fix-accel-length] accelgroup: Fix an invalid write

[Matthias Clasen <matthiasc src gnome org>]

commit ad1bc75dd2cf5cb758e9a12cd0792e850a55fed8
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Apr 10 08:24:03 2020 -0400

    accelgroup: Fix an invalid write
    
    This was lost by accident in d110fddbce14d13c.
    
    Fixes: #2602

 gtk/gtkaccelgroup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/gtk/gtkaccelgroup.c b/gtk/gtkaccelgroup.c
index 0cf685c2d8..964974abb4 100644
--- a/gtk/gtkaccelgroup.c
+++ b/gtk/gtkaccelgroup.c
@@ -592,7 +592,7 @@ gtk_accelerator_name (guint           accelerator_key,
     keyval_name = "";
 
   saved_mods = accelerator_mods;
-  l = 0;
+  l = strlen (keyval_name);
   if (accelerator_mods & GDK_SHIFT_MASK)
     l += sizeof (text_shift) - 1;
   if (accelerator_mods & GDK_CONTROL_MASK)