[cairo] Tracking down stale references to entries in the scaled font map

[Chris Wilson]

Excerpts from Zack Weinberg's message of Mon Aug 03 21:22:54 +0100 2009:
> Can anyone give some tips on how to track down where these stale
> references might be held?

When debugging reference leaks within the library I add source
annotations to give each reference a separate context and then use
valgrind to find the leaked context. (For reference that skin was called
refdbg, but is now part of my memfault skin). That works pretty well so
long as the contexts remain unique, but even then helps narrow down the
possibilities.

Anyway, I hope made some progress here and if you've picked up any tips,
please do share them! :)
-ickle