rustc: Run destructors when dest=Ignore

Previously, if statements of the form "Foo;" or "let _ = Foo;" were encountered
where Foo had a destructor, the destructors were not run. This changes
the relevant locations in trans to check for ty::type_needs_drop and invokes
trans_to_lvalue instead of trans_into.

Closes #4734
Closes #6892
Replace 'region' with 'lifetime' in a few transmute function names
Fixes #13507

Fixes hashing of DefId for ty_enum.

Adds tests for cross-crate TypeId equivalence for various types.
optimized SipHash implementation

work started from @gereeter's PR: https://github.com/mozilla/rust/pull/13114
but adjusted bits
Improve the copying code for slices and Vec
auto merge of #13511 : Meyermagic/rust/enum_typeid, r=alexcrichton

Fixes #13507.

I haven't familiarized myself with this part of the rust compiler, so hopefully there are no mistakes (despite the simplicity of the commit). It is also 5am.
Remove usage of private enum variants

This replaces all uses of private enum variants with a struct that has
one private field pointing at a private enum.

RFC: 0006-remove-priv
auto merge of #13498 : johnsoft/rust/fix-transmute-fn-names, r=alexcrichton

Regions were renamed to lifetimes a while back, so these functions should probably be renamed as well.
Make Vec::clone and slice::to_owned failure-safe
Remove RUST_LOG="::help" from the docs

This feature is no longer present in the current version, it was removed along
with the crate map.
dist: Make Windows installer uninstall first. Closes #9563

This will remove existing files before installing new ones. Note
that I took some code with no license from stackoverflow, as
indicated in comments.
Change AUTHORS section in the man pages

The man pages no longer contain Graydon Hoare as the project lead.

Fix #13509.
Update GitHub's Rust projects page.
mk: Change windows to install from stage2

In the past, windows was installed from stage3 to guarantee convergence between
the host and target artifacts, but syntax extensions on all platforms are
currently relying on convergence, so special casing this one platform has become
less relevant over time.

This will also have the added benefit of dealing with #13474 and #13491. These
issues will be closed after next next nightly is confirmed to fix them.
liburl doc: insert missing hyphen
rustdoc: Better sorting criteria for searching.

This essentially rewrites the sorting algorithm, which relied on
the implementation-defined handling of non-consistent sorting function
(cf. ECMA-262 5th edition, section 15.4.4.11)
and was also a bit inefficient.

The new criteria expands the prior criteria while adding these ones:

- The current crate is always preferred over other crates.
  (Closes #13178)
- An item with a description is preferred over one without it,
  if item names match. This is a heuristic assuming that
  the documented item is more likely to be relevant.
- An item with no literal occurrence of search query is handled correctly.
std: Impl Deref/DerefMut for a borrowed task
native: Be more stringent about pattern matching

Trying to avoid a wildcard where possible.
native: Fix a race in select()

During selection, libnative would erroneously re-acquire ownership of a task
when a separate thread still had ownership of the task. The loop in select()
was rewritten to acknowledge this race and instead block waiting to re-acquire
ownership rather than plowing through.

Closes #13494
Use the unsigned integer types for bitwise intrinsics.

Exposing ctpop, ctlz, cttz and bswap as taking signed i8/i16/... is just
exposing the internal LLVM names pointlessly (LLVM doesn't have "signed
integers" or "unsigned integers", it just has sized integer types
with (un)signed *operations*).

These operations are semantically working with raw bytes, which the
unsigned types model better.