Configure `glib` and `gdk-pixbuf`
Assert that the `cairo` library exists
Don't need these READMEs
Export PKG_CONFIG_PATH instead

Fixes Cairo errors, for Mac OSX at least. See http://git.io/P_Ob8w
Merge pull request #19 from gjtorikian/keep-looking-for-glib

Configure `glib` and `gdk-pixbuf`