[ft] Adding custom font driver?

[Ian Britten]

Hi all,
What's the proper way to add a custom font driver to FT, as a FT
user, not as a FT developer/maintainer? (ie: I can't just modify
a FT build and add my code to the library)

Currently (v2.1.7), we do something similar to this: [ NB - C++ ]
    static const FT_Driver_ClassRec custom_driver = {
             //  Blah blah blah.  Details omitted
    };
    FT_Add_Module(library, &custom_driver);
and this has worked well for us.

Upon trying to upgrade to v2.3.5, I'm finding that the
FT_Driver_ClassRec structure is in freetype/internal/ftdriver.h,
which is no longer publicly accessable.  As such, I'm kindof
stumped about how best to proceed.

Any suggestions welcome!
Ian