[metacity] prefs: don't use define in string concatenation

[Alberts Muktupāvels <muktupavels src gnome org>]

commit a6a8530e1024df8598b518055459032272eba3ce
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Sun Sep 6 14:15:51 2020 +0300

    prefs: don't use define in string concatenation
    
    https://gitlab.gnome.org/GNOME/metacity/-/commit/676fea75be3fefed957a6b67cdb87cff92972895#note_906088

 src/core/prefs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/core/prefs.c b/src/core/prefs.c
index 2aa82c9a..bd13b4df 100644
--- a/src/core/prefs.c
+++ b/src/core/prefs.c
@@ -902,7 +902,7 @@ settings_changed (GSettings *settings,
     }
   else if (strcmp (key, KEY_COMPOSITING_MANAGER) == 0)
     {
-      g_warning (_("Setting “" KEY_COMPOSITING_MANAGER "” is deprecated, "
+      g_warning (_("Setting “compositing-manager” is deprecated, "
                    "use the “compositor” instead."));
 
       update_compositing_manager ();