[libdazzle] shortcut-chord: use const type qualifier

[Christian Hergert <chergert src gnome org>]

commit 9c96dc2ff468b21be5dfb2f851ca8ba26d11df1f
Author: Yi-Soo An <yisooan gmail com>
Date:   Tue Feb 12 14:42:02 2019 +0900

    shortcut-chord: use const type qualifier
    
    Ensure that the value of self is never changed through the method.

 src/shortcuts/dzl-shortcut-chord.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/shortcuts/dzl-shortcut-chord.c b/src/shortcuts/dzl-shortcut-chord.c
index 0d99b6f..a77c0c3 100644
--- a/src/shortcuts/dzl-shortcut-chord.c
+++ b/src/shortcuts/dzl-shortcut-chord.c
@@ -86,7 +86,7 @@ dzl_shortcut_chord_compare (const DzlShortcutChord *a,
 }
 
 static gboolean
-dzl_shortcut_chord_is_valid (DzlShortcutChord *self)
+dzl_shortcut_chord_is_valid (const DzlShortcutChord *self)
 {
   g_assert (IS_SHORTCUT_CHORD (self));