rust.md: Explicitly point out how special `'static` is.

Drive-by: fix description of `&content` to point out that `&'f type`
is (as of today) only for type expressions.
Sort most attributes alphabetically
librustc: Use separate stack slot for each return.
Reenable ignored test and add run-pass test.
librustc: Add an intrinsic to retrieve the return pointer of a function.

This is needed for some GC stuff in Servo.
librustc: Don't allow return_address intrinsic in functions that don't use an out pointer.
librustc: Don't use Load/Store for structural values.
librustc: Don't use an alloca per return if the function doesn't have nested returns.
guide-runtime.md: remove redundant verb
guide-testing.md: add auxiliary verb
guide-unsafe.md: fix noun
Replace all references to "Win32" with "Windows".

For historical reasons, "Win32" has been used in Rust codebase to mean "Windows OS in general".
This is confusing, especially now, that Rust supports Win64 builds.

[breaking-change]
Replace #[cfg(target_os = "win32")] with #[cfg(target_os = "windows")]
Minor changes to `rust.md`, and `guide-ffi.md`.

  * `rust.md`: whanges for consistency

  * `guide-ffi.md`: wrapped inline code
Replace "ignore-win32" in tests with "ignore-windows"
~ -> Box in the manual

Fixes #16439
libsyntax: Don't strip types and lifetimes from single-segment paths in
patterns.

This breaks code like:

    fn main() {
        match Some("foo") {
            None::<int> => {}
            Some(_) => {}
        }
    }

Change this code to not contain a type error. For example:

    fn main() {
        match Some("foo") {
            None::<&str> => {}
            Some(_) => {}
        }
    }

Closes #16353.

[breaking-change]
auto merge of #16081 : luqmana/rust/nr, r=pcwalton

Fixes #15763
guide-unsafe.md: fix wording

Following a suggestion by Huon Wilson.
auto merge of #16454 : pcwalton/rust/types-in-path-patterns, r=brson

patterns.

This breaks code like:

    fn main() {
        match Some("foo") {
            None::<int> => {}
            Some(_) => {}
        }
    }

Change this code to not contain a type error. For example:

    fn main() {
        match Some("foo") {
            None::<&str> => {}
            Some(_) => {}
        }
    }

Closes #16353.

[breaking-change]

r? @huonw