add an experimental tag for Gc<T> due to cycles

This type isn't yet very useful since it only pretends cycles won't be
a problem. Anyone using it should be made aware that they're going to
leak.
remove reference counting headers from ~

Unique pointers and vectors currently contain a reference counting
header when containing a managed pointer.

This `{ ref_count, type_desc, prev, next }` header is not necessary and
not a sensible foundation for tracing. It adds needless complexity to
library code and is responsible for breakage in places where the branch
has been left out.

The `borrow_offset` field can now be removed from `TyDesc` along with
the associated handling in the compiler.

Closes #9510
Closes #11533
remove `borrow_offset` as ~ is now free of headers
add implementation of `Repr` for `~[T]`
Mark LineIterator as public so its docs get generated.
extra: Ignore time tests on android correctly
Flag failure functions as inline(never)

The failure functions are generic, meaning they're candidates for getting
inlined across crates. This has been happening, leading to monstrosities like
that found in #11549. I have verified that the codegen is *much* better now that
we're not inlining the failure path (the slow path).
auto merge of #11535 : thestinger/rust/header, r=alexcrichton

Unique pointers and vectors currently contain a reference counting
header when containing a managed pointer.

This `{ ref_count, type_desc, prev, next }` header is not necessary and
not a sensible foundation for tracing. It adds needless complexity to
library code and is responsible for breakage in places where the branch
 has been left out.

The `borrow_offset` field can now be removed from `TyDesc` along with
the associated handling in the compiler.

Closes #9510
Closes #11533
libstd: Added more #[inline] annotations and replaced uses of `libc::abort` with the intrinsic.
auto merge of #11557 : brson/rust/anotherandroidfix, r=thestinger
Fix formatting in rust-guide document.
auto merge of #11556 : am0d/rust/docs, r=huonw
register snapshots
remove the concept of managed-unique from libstd

Closes #11545
auto merge of #11561 : eddyb/rust/moar-inlines, r=pcwalton
auto merge of #11564 : am0d/rust/dox, r=huonw

Needs a line break here for readability.
Add a configure to disable libstd version injection

We'll use this when building snapshots so we can upgrade freely, but all
compilers will inject a version by default.
Revert "show options for -W help and -W". Fixes #11458.

This reverts commit 1009c21ad7b1db366a5c600946652cc490598ec1.
auto merge of #11523 : alexcrichton/rust/stage3, r=brson

This should go back to the old behavior while preserving the snapshot ease.
Use the least significant beat to determine if int/uint is even