Fix some typos.
Move time out of extra (cc #8784)
auto merge of #12411 : Arcterus/rust/time, r=alexcrichton

More work towards finishing #8784.
auto merge of #12421 : Hywan/rust/api_doc, r=alexcrichton

I was reading the code and saw this. Not the best contribution of my life ;-).
std: Move intrinsics to std::intrinsics.

Issue #1457
std: Move raw to std::raw

Issue #1457
std: Remove unstable::lang

Put the lonely lang items here closer to the code they are calling.
std: Move unstable::stack to rt::stack