[gnome-calendar] event: don't leak event description

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 3be142a2073c17e55dd41ece5884197cde1757c3
Author: Mohammed Sadiq <sadiq sadiqpk org>
Date:   Mon Apr 17 16:53:58 2017 +0530

    event: don't leak event description
    
    https://bugzilla.gnome.org/show_bug.cgi?id=781400

 src/gcal-event.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/src/gcal-event.c b/src/gcal-event.c
index 907bb96..1a06a84 100644
--- a/src/gcal-event.c
+++ b/src/gcal-event.c
@@ -992,6 +992,7 @@ gcal_event_set_description (GcalEvent   *self,
       ECalComponentText text_component;
       GSList list;
 
+      g_clear_pointer (&self->description, g_free);
       self->description = g_strdup (description);
 
       text_component.value = description;