Simple library initialization

[Andrei Alexandrescu via Digitalmars-d]

Walter and I investigated a bit the way C module 
initialization/termination works. 
https://issues.dlang.org/show_bug.cgi?id=17035 is the result.

This preapproved enhancement would make life easier for folks who want 
to write libraries that don't depend on druntime.


Andrei