Fix a build warning.
Fix a build warning.

sharoonthomas/gtk-mac-integration,rhult/ige-mac-integration,GNOME/gtk-mac-integration,rhult/ige-mac-integration,sharoonthomas/gtk-mac-integration,GNOME/gtk-mac-integration,jralls/gtk-mac-integration,sharoonthomas/gtk-mac-integration,sharoonthomas/gtk-mac-integration,rhult/ige-mac-integration,sharoonthomas/gtk-mac-integration,GNOME/gtk-mac-integration,jralls/gtk-mac-integration,jralls/gtk-mac-integration