Issue #9629 -- permit freezing `&mut` found within an `&` pointer
std::rand: move normal and exponential to their own file.
std::rand: implement the log-normal distribution.
rustdoc: fix the search-bar layout

Now with broader compatibility.
Register new snapshots

This transitions the snapshot dependency process to understand that our
snapshots are now a single static binary rather than an array of files.
Add dead-code warning pass
Remove dead codes
std::rand: implement the chi-squared distribution.
std::rand: implement the F distribution.
std::rand: implement the student t distribution.
auto merge of #10855 : alexcrichton/rust/snapshots, r=pcwalton

This transitions the snapshot dependency process to understand that our
snapshots are now a single static binary rather than an array of files.
auto merge of #10477 : ktt3ja/rust/dead-code, r=alexcrichton

PR for issue #1749 mainly to get some feedback and suggestion. This adds a pass that warns if a function, struct, enum, or static item is never used. For the following code,

```rust
pub static pub_static: int = 0;
static priv_static: int = 0;
static used_static: int = 0;

pub fn pub_fn() { used_fn(); }
fn priv_fn() { let unused_struct = PrivStruct; }
fn used_fn() {}

pub struct PubStruct();
struct PrivStruct();
struct UsedStruct1 { x: int }
struct UsedStruct2(int);
struct UsedStruct3();

pub enum pub_enum { foo1, bar1 }
enum priv_enum { foo2, bar2 }
enum used_enum { foo3, bar3 }

fn foo() {
	bar();
	let unused_enum = foo2;
}

fn bar() {
	foo();
}

fn main() {
	let used_struct1 = UsedStruct1 { x: 1 };
	let used_struct2 = UsedStruct2(1);
	let used_struct3 = UsedStruct3;
	let t = used_static;
	let e = foo3;
}
```

it would add the following warnings:

```rust
/home/ktt3ja/test.rs:2:0: 2:28 warning: code is never used: `priv_static`, #[warn(dead_code)] on by default
/home/ktt3ja/test.rs:2 static priv_static: int = 0;
                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/ktt3ja/test.rs:6:0: 6:48 warning: code is never used: `priv_fn`, #[warn(dead_code)] on by default
/home/ktt3ja/test.rs:6 fn priv_fn() { let unused_struct = PrivStruct; }
                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/ktt3ja/test.rs:10:0: 10:20 warning: code is never used: `PrivStruct`, #[warn(dead_code)] on by default
/home/ktt3ja/test.rs:10 struct PrivStruct();
                        ^~~~~~~~~~~~~~~~~~~~
/home/ktt3ja/test.rs:16:0: 16:29 warning: code is never used: `priv_enum`, #[warn(dead_code)] on by default
/home/ktt3ja/test.rs:16 enum priv_enum { foo2, bar2 }
                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/ktt3ja/test.rs:19:0: 22:1 warning: code is never used: `foo`, #[warn(dead_code)] on by default
/home/ktt3ja/test.rs:19 fn foo() {
/home/ktt3ja/test.rs:20 	bar();
/home/ktt3ja/test.rs:21 	let unused_enum = foo2;
/home/ktt3ja/test.rs:22 }
/home/ktt3ja/test.rs:24:0: 26:1 warning: code is never used: `bar`, #[warn(dead_code)] on by default
/home/ktt3ja/test.rs:24 fn bar() {
/home/ktt3ja/test.rs:25 	foo();
/home/ktt3ja/test.rs:26 }
```

Furthermore, I would like to solicit some test cases since I haven't tested extensively and I'm still unclear about some of the things in here. For example, I'm not sure how reexports would affect this and just assumed that LiveContext (which is a copy of reachable::ReachableContext) does enough work to handle it. Also, the test case above doesn't include any impl or methods, etc.
encode trait lifetime params in metadata to allow cross-crate usage
auto merge of #10813 : dwrensha/rust/xcrate-lifetime-param, r=huonw

Before applying this patch, the included testcase fails with:
```
src/test/run-pass/xcrate-trait-lifetime-param.rs:20:10: 20:28 error: wrong number of lifetime parameters: expected 0 but found 1
src/test/run-pass/xcrate-trait-lifetime-param.rs:20 impl <'a> other::FromBuf<'a> for Reader<'a> {
                                                              ^~~~~~~~~~~~~~~~~~
```

There's another example in my comments to #10506.
Fix comment on ast::DefStruct
auto merge of #10866 : ktt3ja/rust/edit-doc, r=huonw

A comment that I previously added to ast::DefStruct is incorrect. Here's the modification.
Accept unsugared docs in missing-doc lint

Closes #10853
Use LLVM integrated assembler on Windows too.
Disable failing test.
Add defun motions for rust-mode.

Specifically, we can now use:
+ beginning-of-defun
+ end-of-defun
+ mark-defun

where "defun" means a Rust item.

+ Add tests in rust-mode-tests.el
+ Fix indentation in rust-mode-tests.el
+ Add support for trait to Imenu