Note to self, and other sysadmins:
To get libgdiplus working, make sure glib-2.0 is installed, that it has a lib64 .pc in pkgconfig, and that there is a symlink from the .so to the real library in /lib64.
<add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient"
description=".Net Framework Data Provider for MySQL"
type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Version=6.2.3.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d"/>
<add name="PostgreSQL Data Provider" invariant="Npgsql" support="FF"
description=".Net Framework Data Provider for PostgreSQL"
type="Npgsql.NpgsqlFactory, Npgsql, Version=2.0.9.0, Culture=neutral, PublicKeyToken=5d8b90d52f46fda7"/>