[tracker] tracker-store: Avoid duplicate timeout removal

[Sam Thursfield <sthursfield src gnome org>]

commit f39098e1729737b4f4e6a49bc8a42e75f01606a7
Author: Sam Thursfield <sam afuera me uk>
Date:   Mon Jun 13 22:29:26 2016 +0100

    tracker-store: Avoid duplicate timeout removal
    
    I kept seeing warnings like this in the 200-backup-restore
    functional-test:
    
        test_backup_01 (__main__.BackupRestoreTest) ...
        (tracker-store:8104): GLib-CRITICAL **: Source ID 25 was not found when attempting to remove it
        test_backup_02 (__main__.BackupRestoreTest) ...
        (tracker-store:8104): GLib-CRITICAL **: Source ID 25 was not found when attempting to remove it

 src/tracker-store/tracker-resources.vala |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/src/tracker-store/tracker-resources.vala b/src/tracker-store/tracker-resources.vala
index f0c57b6..9b771fa 100644
--- a/src/tracker-store/tracker-resources.vala
+++ b/src/tracker-store/tracker-resources.vala
@@ -352,6 +352,7 @@ public class Tracker.Resources : Object {
 
                if (signal_timeout != 0) {
                        Source.remove (signal_timeout);
+                       signal_timeout = 0;
                }
        }