Save types of local vars too in save_class_state

[RealyUniqueName]

Fixes #4073

gencs/genjava actively mess with types, so I ended up just saving/restoring that data.

[Simn]

But we already do that in save_class_state. Is there something specific that isn't saved there?

[RealyUniqueName]

Types of local vars and function arguments.
Also, gencs/genjava mess with cl_restore too and that breaks subsequent compilation somehow.

[RealyUniqueName]

I mean, using save_class_state upon entering genjs/genjava and cl.cl_restore upon leaving them. I tried that and subsequent compilations started throwing Not_found ocaml exception.

[Simn]

Yes you're not supposed to run it at that point.

What we should do is handle the tvars there so it's all in one place. Maybe only on targets where it's necessary, but it might be a good idea to always do this.

[RealyUniqueName]

Yeah, that works. I've updated this PR