[tex-live] siunitx needs expl3 update

[Karl Berry]

Hi Joseph,

    Perhaps the backlog of updates after the TL2011 release has led to
    a timing issue?

I forgot that siunitx needed the new l3* stuff.

I've now installed l3kernel, l3packages, l3experimental, and removed
xpackages and expl3.  Let me know if other stuff should be done in this
regard.

Thanks,
karl