Security update for xml-security-c

[Florian Weimer]

* Russ Allbery:

> I have uploaded 1.4.0-3+lenny2 to the right queue this time.

Thanks!

> I've also prepared a fix for oldstable.  This fix is a bit different
> because the code had been reorganized after 1.2.1, and the old package was
> using quilt.  Below is the diff; let me know if this looks good and I'll
> upload it as well.

It looks okay.  Please upload.