Also, we now verify the version script is correct each time we run the tests;
the consequences of getting the version script wrong are terribly bad.
Note, we can't actually use generated .map file for two reasons:
1. We don't hard depend on GObject Introspection
2. The map file is required to build the lib that the GIR is built from
To avoid the circular dep, and to ensure we don't change exported API
accidentaly actually check in a version of the version script to git.
