gobject-introspection: Override GIO_MODULE_DIR when scanning
This is to stop GLib linking to GConf and other modules (e.g gnutls).
If for example gconf is installed in the sysroot then GLib will use it by
default for the GSettings backend. This will pull a lot more libraries into the
scanner processes and expands the potential for runtime issues since dependencies
may be missing of change since they're not in the dependency chain.
Use an invalid modules directory so we avoid loading any modules or the
libraries they link against which the system may be in the process of rebuilding.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
