Custom runtime adventures

[p0nce]

Advice from Hipreme:

A druntime lives here: https://github.com/MrcSnm/webassembly/tree/vita

Using that could be super interesting for portability.

• For wasm: two clang+libc offer exist, but , no effort from OS vendors to have some kind of wasi libc of their own it seems. OTOH we don't need whole of libc at all. It start becoming a bit daunting maybe.
• Not sure how to avoid druntime/phobos with non-wasm build in general.
• Not sure if we need VFS abstraction before this.