[simple-scan] Make string translatable as plural.

[Robert Ancell <rancell src gnome org>]

commit 335dd4d5fb274730221ff3c72969aeb432665f64
Author: Robert Ancell <robert ancell canonical com>
Date:   Mon May 22 15:12:14 2017 +1200

    Make string translatable as plural.
    
    Fixes https://bugzilla.gnome.org/show_bug.cgi?id=782147

 src/app-window.vala |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/app-window.vala b/src/app-window.vala
index 159444b..4d32d97 100644
--- a/src/app-window.vala
+++ b/src/app-window.vala
@@ -1463,7 +1463,7 @@ public class AppWindow : Gtk.ApplicationWindow
             });
 #else
             instructions_label.set_text (/* Label shown to prompt user to install packages (when PackageKit 
not available) */
-                                         _("You need to install the %s package(s).").printf (string.joinv 
(", ", packages_to_install)));
+                                         ngettext ("You need to install the %s package.", "You need to 
install the %s packages.", packages_to_install.length).printf (string.joinv (", ", packages_to_install)));
 #endif
         }