Change 'Example' to 'Examples' throughout collections' rustdocs.
Clean up `libcollections::VecMap`

- Introduce a named type for the return type of `VecMap::move_iter`
- Rename all type parameters to `V` for "Value".
- Remove unnecessary call to an `Option::unwrap`, use pattern matching instead.
- Remove incorrect `Hash` implementation which took the `VecMap`'s capacity
  into account.

This is a [breaking-change], however whoever used the `Hash` implementation
relied on an incorrect implementation.
Add a proper `Hash` implementation for `VecMap`

Also re-add the previously deleted test with an additional test that would have
failed before, when the hash function depended on the capacity.
auto merge of #19655 : jbranchaud/rust/change-example-to-examples, r=steveklabnik

@steveklabnik I got a start on this.
auto merge of #19663 : tbu-/rust/pr_fix_vecmap, r=Gankro

- Introduce a named type for the return type of `VecMap::move_iter`
- Rename all type parameters to `V` for "Value".
- Remove unnecessary call to an `Option::unwrap`, use pattern matching instead.
- Remove incorrect `Hash` implementation which took the `VecMap`'s capacity
  into account.

This is a [breaking-change], however whoever used the `Hash` implementation
relied on an incorrect implementation.
rustc: Fix `make install`

Move a few docblocks from 'ignore' to something that's not rust (e.g. 'text').

Closes #19678
Don't try to dist src/README.md which does not exist
auto merge of #19705 : brson/rust/fix-install, r=alexcrichton
Start restructuring to support generalized where clauses etc.
Thread a id to `Obligation`
Move the list of region obligations into the fulfillment context.
Introduce predicates but don't use them.
Write code for registering region obligations (but don't use it yet).
Switch to using predicates to drive checking. Correct various tests --
in most cases, just the error message changed, but in some cases we
are reporting new errors that OUGHT to have been reported before but
we're overlooked (mostly involving the `'static` bound on `Send`).
Remove diagnostic errors that were yielding warnings.
Fix the opt-out-copy behavior so that values with dtor etc are considered affine
Implement the astencode rules for predicates. These don't actually get
used by trans, but it's easy to do.
Improve comments and address nits.