We just want to be able to build glib from the within the pkg-config
tree. Everything else is just extra weight and is better used from an
actual glib checkout. Unnecessary files include:
* documentation
* translations
* tests
* ChangeLogs
* non-autotools win32 build files
* various other build and/or internal files
Grab a snapshot of a tag from a local glib checkout, remove a bunch of
files and apply some patches. The idea is to make the snapshot of glib
be repeatable.