Add example of estimating pi using Monte Carlo simulation to std::rand
Remove the dist function; it is more efficient to compare squared distances
libcore: Get rid of useless mem::forget wrapper.
Change how libgetopts handles options grouped together

As soon as an option is found that takes an argument, consume the rest
of the string and store it into i_arg. Previously this would only happen
if the character after the option was not a recognized option.

Addresses issue #16348
Guide: ownership
librustc: When checking static method calls to unboxed closures, look at
the right trait and take the method name into account.

Closes #16599.
librustc: Fix bogus logic for static calls to unboxed closures in the
expression use visitor.

Closes #16166.
Make note that Ordering is builtin.

This way people won't try to copy/paste it in.
librustc: Fix a couple of cases in which unboxed closure typechecking
code wasn't considering the zero-argument case.

Closes #16168.
docs: don't claim struct layout is specified, but mention repr
librustc: handle repr on structs, require it for ffi, unify with packed

As of RFC 18, struct layout is undefined. Opting into a C-compatible struct
layout is now down with #[repr(C)]. For consistency, specifying a packed
layout is now also down with #[repr(packed)]. Both can be specified.

To fix errors caused by this, just add #[repr(C)] to the structs, and change
 #[packed] to #[repr(packed)]

Closes #14309

[breaking-change]
Add #[repr(C)] to all the things!
manual: fix link
Add detailed note about Substs to ty_enum
liblibc: don't use int/uint for intptr_t/uintptr_t

int/uint aren't considered FFI safe, replace them with the actual type they
represent (i64/u64 or i32/u32). This is a breaking change, but at most a cast
to `uint` or `int` needs to be added.

[breaking-change]
libgreen: use FFI-safe types
Stage #[repr(packed)] in std::rt
Surround formula in a 'notrust' code block
Use unicode pi symbol in pi estimation example. Additional tweaks
auto merge of #16362 : nham/rust/std_rand_pi_example, r=huonw

Pros:
I like this example because it's concise without being trivial. The Monty Hall example code is somewhat lengthy and possibly inaccessible to those unfamiliar with probability.

Cons:
The Monty Hall example already exists. Do we need another example? Also, this is probably inaccessible to people who don't know basic geometry.