[plt-scheme] _loader ?

Is anyone using the "_loader" protocol for combining multiple modules
into a single shared object?

I've started removing support for it in v3.99, but it's not to late to
add it back if there's an important use for it. The "_loader" protocol
is a hold-over from our early days trying to compile Scheme via C, and
I doubt that it found any real uses.

Thanks,
Matthew