Patch to avoid history duplicates applied

[Pavel Roskin]

Hello!

> Yes, it was a simple mistake.  Even the comment "return pointer to last
> entry in list" was preserved, but the code actually doing it disappeared
> during conversion.

One more bug was in list_append_unique() that could kill the directory
history if you started mc in the directory that was the last in history.

I consider this a bug in glib (function g_list_remove_link), and it will
be reported.

-- 
Regards,
Pavel Roskin