Update to TeXLive 2011 needs protected caption subrefs

Update to TeXLive 2011 needs protected caption subrefs

To avoid:

  ! Argument of \@caption has an extra }.

fragile \subref{} calls in \caption{} arguments need to be
\protect-ed.  For details, see:

  http://tex.stackexchange.com/questions/31817/texlive-2011-and-subfig

where egreg points out that the change probably happened in the bump
to caption 3.2.