inode-based dlopen caching

[Florian Weimer]

* Adhemerval Zanella:

> But my main reservation with this is the idea of reload the new module
> is, although the symbol resolution is a different namespace, it still
> share the same process resources.  It would require a lot of careful
> code within the library so it can run with multiple instances, we see
> the potential issues with our static dlopen support.

It would work quite well for a lot of stateless JNI wrappers or Python
extensions, though.  That alone looks like a relevant use case to me.

Thanks,
Florian