[gnome-software] Fix NULL pointer warnings if polkit disabled

[Alexander Larsson <alexl src gnome org>]

commit 89caabaa0a2ec3a581410d10f01d0811214890a6
Author: Alexander Larsson <alexl redhat com>
Date:   Wed Feb 10 10:28:47 2016 +0100

    Fix NULL pointer warnings if polkit disabled
    
    gs_update_monitor_permission_get() can return NULL if there is
    no polkit support. Handle this.

 src/gs-application.c   |    5 +++--
 src/gs-shell-updates.c |    5 +++--
 src/gs-shell.c         |    5 +++--
 3 files changed, 9 insertions(+), 6 deletions(-)
---
diff --git a/src/gs-application.c b/src/gs-application.c
index 3136217..71f6f66 100644
--- a/src/gs-application.c
+++ b/src/gs-application.c
@@ -148,8 +148,9 @@ gs_application_monitor_permission (GsApplication *app)
        GPermission *permission;
 
        permission = gs_update_monitor_permission_get ();
-       g_signal_connect (permission, "notify",
-                         G_CALLBACK (on_permission_changed), app);
+       if (permission != NULL)
+               g_signal_connect (permission, "notify",
+                                 G_CALLBACK (on_permission_changed), app);
 }
 
 static void
diff --git a/src/gs-shell-updates.c b/src/gs-shell-updates.c
index 08e83bd..ec5c9fd 100644
--- a/src/gs-shell-updates.c
+++ b/src/gs-shell-updates.c
@@ -951,8 +951,9 @@ gs_shell_updates_monitor_permission (GsShellUpdates *self)
         GPermission *permission;
 
         permission = gs_update_monitor_permission_get ();
-        g_signal_connect (permission, "notify",
-                          G_CALLBACK (on_permission_changed), self);
+       if (permission != NULL)
+               g_signal_connect (permission, "notify",
+                                 G_CALLBACK (on_permission_changed), self);
 }
 
 void
diff --git a/src/gs-shell.c b/src/gs-shell.c
index c2ae9f2..62aff1b 100644
--- a/src/gs-shell.c
+++ b/src/gs-shell.c
@@ -556,8 +556,9 @@ gs_shell_monitor_permission (GsShell *shell)
         GPermission *permission;
 
         permission = gs_update_monitor_permission_get ();
-        g_signal_connect (permission, "notify",
-                          G_CALLBACK (on_permission_changed), shell);
+       if (permission != NULL)
+               g_signal_connect (permission, "notify",
+                                 G_CALLBACK (on_permission_changed), shell);
 }
 
 /**