syntax: Fix span on illegal ABI errors

Fixes #8537
Fixes #14499
Change to_owned() to to_string().
Make Arc::make_unique check weak refs; add make_unique to Rc

This patch makes `Arc::make_unique` examine the number of weak
references as well as strong references, which is required for safety.

It also adds a `make_unique` method to the `Rc` type for consistency.

Closes #14521.
Implement Show for Bitv{,Set}

Closes #14531
Fix the handling of assignments to owning pointer paths in check_loans

Make check_for_assignment_to_restricted_or_frozen_location treat
mutation through an owning pointer the same way it treats mutation
through an &mut pointer, where mutability must be inherited from the
base path.

I also included GC pointers in this check, as that is what the
corresponding code in gather_loans/restrictions.rs does, but I don't
think there is a way to test this with the current language.

Fixes #14498.
auto merge of #14517 : lucy/rust/issue-14499, r=alexcrichton

Fixes #8537
Fixes #14499 (duplicate of #8537)

Old:
```rust
test.rs:2 	pub extern "xxxxx" fn add(x: int, y: int) -> int {
          	                   ^~
```

New:
```rust
test.rs:2 	pub extern "xxxxx" fn add(x: int, y: int) -> int {
          	           ^~~~~~~
```
auto merge of #14522 : aturon/rust/make_unique, r=alexcrichton,alexcrichton,me

This patch makes `Arc::make_unique` examine the number of weak
references as well as strong references, which is required for safety.

It also adds a `make_unique` method to the `Rc` type for consistency.

Closes #14521.
auto merge of #14524 : ahmedcharles/rust/to_string, r=alexcrichton
auto merge of #14535 : sfackler/rust/bitv-show, r=alexcrichton

Closes #14531
rustc: Add lint for snake_case functions & methods.
libsyntax: Fix snake_case errors.

A number of functions/methods have been moved or renamed to align
better with rust standard conventions.

syntax::ext::mtwt::xorPush => xor_push
syntax::parse::parser::Parser => Parser::new

[breaking-change]
lib{std,core,debug,rustuv,collections,native,regex}: Fix snake_case errors.

A number of functions/methods have been moved or renamed to align
better with rust standard conventions.

std::reflect::MovePtrAdaptor => MovePtrAdaptor::new
debug::reflect::MovePtrAdaptor => MovePtrAdaptor::new
std::repr::ReprVisitor => ReprVisitor::new
debug::repr::ReprVisitor => ReprVisitor::new
rustuv::homing::HomingIO.go_to_IO_home => go_to_io_home

[breaking-change]
lib{serialize, uuid}: Fix snake case errors.

A number of functions/methods have been moved or renamed to align
better with rust standard conventions.

serialize::ebml::reader::Doc => seriaize::ebml::Doc::new
serialize::ebml::reader::Decoder => Decoder::new
serialize::ebml::writer::Encoder => Encoder::new

[breaking-change]
librustc: Fix snake case errors.

A number of functions/methods have been moved or renamed to align
better with rust standard conventions.

rustc::back::link::WriteOutputFile => write_output_file
rustc::middle::ty::EmptyBuiltinBounds => empty_builtin_bounds
rustc::middle::ty::AllBuiltinBounds => all_builtin_bounds
rustc::middle::liveness::IrMaps => IrMaps::new
rustc::middle::liveness::Liveness => Liveness::new
rustc::middle::resolve::NameBindings => NameBindings::new
rustc::middle::resolve::PrimitiveTypeTable => PrimitiveTypeTable::new
rustc::middle::resolve::Resolver => Resolver::new
rustc::middle::trans::datum::Datum => Datum::new
rustc::middle::trans::datum::DatumBlock => DatumBlock::new
rustc::middle::trans::datum::Rvalue => Rvalue::new
rustc::middle::typeck::infer::new_ValsAndBindings => ::infer::unify::ValsAndBindings::new
rustc::middle::typeck::infer::region_inference::RegionVarBindings => RegionVarBindings::new

[breaking-change]
windows: Allow snake_case errors for now.
auto merge of #14520 : Ryman/rust/SnakeCaseLint, r=alexcrichton

This enforces `snake_case` for functions and methods only. Might be worth extending it to fields and locals too at some point in the future.

A number of breaking changes each detailed in the attached commits.
Ignore /build even if it’s a symlink, but only at top-level.
Remove deprecated owned vector from iterator example.
auto merge of #14536 : zwarich/rust/issue-14498, r=luqmana

Make check_for_assignment_to_restricted_or_frozen_location treat
mutation through an owning pointer the same way it treats mutation
through an &mut pointer, where mutability must be inherited from the
base path.

I also included GC pointers in this check, as that is what the
corresponding code in gather_loans/restrictions.rs does, but I don't
think there is a way to test this with the current language.

Fixes #14498.
auto merge of #14546 : SimonSapin/rust/patch-13, r=alexcrichton

CC @alexcrichton
Closes #14545