[llvm-dev] LLD: time to enable --threads by default

[Rafael Espíndola via llvm-dev]

> Sounds like threading isn't beneficial much beyond the second CPU...
> Maybe blindly creating one thread per core isn't the best plan...

parallel.h is pretty simplistic at the moment. Currently it creates
one per SMT. One per core and being lazy about it would probably be a
good thing, but threading is already beneficial and improving
parallel.h an welcome improvement.

Cheers,
Rafael