Comment 52 for bug 1030357

Here's the upstream git log for cairo-cff-subset.c :

  http://cgit.freedesktop.org/cairo/log/src/cairo-cff-subset.c

The attached patch collects the five changes between 2012-06-07 and 2012-07-31.

The valgrind warning may not be needed, but it seemed safer to me to take all his updates to this point, together, given that the result looks quite stable. More testing would be great, of course. Thanks!