Can we use "ImportC" used yet?

[rempas via Digitalmars-d-learn]

Cause I can't find an option in the latest DMD release and 
because the ImportC 
[page](https://dlang.org/spec/importc.html#importing) seems to be 
incomplete (even saying it's under construct), I'm wondering if 
ImportC exists even as prototype but it's hidden or if it's not 
available at all. Anyone knows?