[gtk/gbsneto/install-header] boxlayout: Correctly define the last property

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit e6bf8792b7bfbbbdec0981069e61eb4425d0770d
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Wed Mar 27 23:23:07 2019 -0300

    boxlayout: Correctly define the last property
    
    Using LAST_PROP = PENULT_PROP is wrong; the GParamSpec array
    will have one less element than it should.
    
    Fix that by not assingning LAST_PROP, and thus increasing its
    size by one.

 gtk/gtkboxlayout.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/gtk/gtkboxlayout.c b/gtk/gtkboxlayout.c
index 0b88e39fcf..7f9bda1053 100644
--- a/gtk/gtkboxlayout.c
+++ b/gtk/gtkboxlayout.c
@@ -69,7 +69,7 @@ enum {
   /* From GtkOrientable */
   PROP_ORIENTATION,
 
-  N_PROPS = PROP_ORIENTATION
+  N_PROPS
 };
 
 static GParamSpec *box_layout_props[N_PROPS];