Remove rust_unwind.h

Adds the required definitions in the correct place.
Merge branch 'incoming' of git://github.com/mozilla/rust into unwind-fix
libstd: impl Integer for BigUint/BigInt.

Also remove abs() method from the non-trait impl for BigInt/BigUint.
That method is provided in the Signed trait.
libstd: inlining almost every methods in bigint module.
auto merge of #6092 : gifnksm/rust/impl-integer-bigint, r=graydon

This is a follow-up commit for #6041 (and depending on #6048).
Also adding `#[inline(always)]` for almost every methods in `std::bigint`.
auto merge of #5646 : Aatch/rust/unwind-fix, r=brson

This fixes issue #5641
make way for a new iter module
auto merge of #6056 : thestinger/rust/iter, r=catamorphism

The existing adaptors like `map` in the `iter` module are very flawed because they only work for `BaseIter` implementations. There are many internal iterator implementations in the standard library like the set methods (`difference`, `symmetric_difference`, `intersection`, `union`) and the `range` functions that only share the `for` loop protocol in common.

The internal iterator adaptors should be implemented to work on any implementation of that protocol, rather than just a method called `each` taking `&self`.

This just moves `iter.rs` to `old_iter.rs` and begins work on documenting and implementing a nicer module.
Re-implement lint with less emphasis on item ids

This way it's much easier to add lints throughout compilation correctly, and
functions on impls can alter the way lints are emitted.