mxcl/homebrew — pull request #14489 by 2bits (2012-08-27 23:32:11+00:00)
Title: librsvg: prepend cairo.pc path to PKG_CONFIG_PATH

librsvg depends on gtk, and when pkgconfig checks gtk-2.0.pc it
queries cairo.pc. The problem is that cairo.pc is prepended
to PKG_CONFIG_PATH on 10.7 because cairo is keg-only. On 10.8
cairo is not keg-only. So there is no prepend, causing compile
errors.

Add a prepend to PKG_CONFIG_PATH to the keg directory for cairo.pc.
Tested on 10.8.1 using XCode-4.4.1, XQuartz-2.7.2, and clang.

Fixes #14474