[Cairo] Cairo API change: cairo_get_* -> cairo_current_*

[Keith Packard]

Around 16 o'clock on Sep 4, Owen Taylor wrote:

> I might suggest simply breaking stuff and letting people fix.
> Cairo isn't mature enough yet to clutter the source code with
> fancy ways of doing deprecation, IMHO.

It is nice to understand how this mechanism will affect future library 
releases now though.  Think of this as practice for deprecating stuff after 
1.0 ships.

I'd suggest that the 1.0 release be accompanied by an elimination of the 
deprecated functions so that we start clean at that point.

-keith