[xml] Win32 bug

["Jens Oknelid" <Jens Oknelid tat se>]

Hi all,

I've been working on a project using libxml on Win32 and I've found a
small bug. InitializeCriticalSection(&cleanup_helpers_cs) needs to be
called once somewhere before starting threads otherwise you'll get a
crash with the message "can't access memory at 0x00000010" or something
like that. I did it in threads.c at row 902 but you may want to do it
someplace else, I'm not too familiar with the structure of this project.
I just thought I'd let you know.

BR,
Jens Oknelid