[gcompris] trying to avoid a crash case in the menu.

[Bruno Coudoin <bcoudoin src gnome org>]

commit bf10f0658b71ed9054efc13f2d188a560adb7aad
Author: Bruno Coudoin <bruno coudoin gcompris net>
Date:   Sat Jan 10 23:21:22 2015 +0100

    trying to avoid a crash case in the menu.
    
    The fix tries to avoid this crash case that I cannot reproduce.
    https://bugzilla.gnome.org/page.cgi?id=trace.html&trace_id=232877

 src/boards/menu2.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/src/boards/menu2.c b/src/boards/menu2.c
index 7b64200..b58e68a 100644
--- a/src/boards/menu2.c
+++ b/src/boards/menu2.c
@@ -420,7 +420,9 @@ menu_end ()
   boardRootItem     = NULL;
   actualSectionItem = NULL;
 
-  g_list_free(panelBoards);
+  if(panelBoards)
+    g_list_free(panelBoards);
+  panelBoards = NULL;
 
 }