Append missing padding after last field of struct

This patch fixes issue #13186.

When generating constant expression for enum, it is possible that
alignment of expression may be not equal to alignment of type.  In that
case space after last struct field must be padded to match size of value
and size of struct. This commit adds that padding.

See detailed explanation in src/test/run-pass/trans-tag-static-padding.rs
Be more clear about what this lambda expression does
Give more explanation when introducing closures
Demonstrate accessing external variable in first example
Some more closure changes
use option_env! instead of env!
Pre-step towards issue #12624 and others: Introduce ExprUseVisitor, remove the
moves computation. ExprUseVisitor is a visitor that walks the AST for a
function and calls a delegate to inform it where borrows, copies, and moves
occur.

In this patch, I rewrite the gather_loans visitor to use ExprUseVisitor, but in
future patches, I think we could rewrite regionck, check_loans, and possibly
other passes to use it as well. This would refactor the repeated code between
those places that tries to determine where copies/moves/etc occur.
Convert delegate to use an object type and remove FIXME from closed issue
Update FFI signature table to use pipe format

Rustdoc doesn't seem like it's converting the old format to a table as we can see here:
http://static.rust-lang.org/doc/master/complement-cheatsheet.html#ffi-(foreign-function-interface)
This new format should fix that and it's also rendered by Github's markdown preview.
Tests for dynamic regexes will now run during 'check-stage2'.

Before, tests for dynamic regexes ran during stage1 and tests for
native regexes ran during stage2. But the buildbots don't test stage1,
so now both dynamic and native tests are run during stage2.

Closes #13740.
rustc: Restrict the scope of a borrow on def_map

This addresses the ICE from #13763, but it does not allow the test to compile,
due to #13768. An alternate test was checked in in the meantime.

Closes #13763
clarify docs for std:io::fs::Path::{is_dir,is_file,exists}; add lstat

Clarifies the interaction of `is_dir`, `is_file` and `exists` with
symbolic links.  Adds a convenience `lstat` function alongside of
`stat`.  Removes references to conditions.

Closes issue #12583.
auto merge of #13750 : aturon/rust/issue-12583, r=alexcrichton

Clarifies the interaction of `is_dir`, `is_file` and `exists` with
symbolic links.  Adds a convenience `lstat` function alongside of
`stat`.  Removes references to conditions.

Closes issue #12583.
auto merge of #13758 : sodaplayer/rust/patch-1, r=alexcrichton

Rustdoc doesn't seem like it's converting the old format to a table as we can see here:
http://static.rust-lang.org/doc/master/complement-cheatsheet.html#ffi-(foreign-function-interface)
This new format should fix that and it's also rendered by Github's markdown preview.
auto merge of #13766 : BurntSushi/rust/regex-dynamic-tests, r=alexcrichton

Before, tests for dynamic regexes ran during stage1 and tests for
native regexes ran during stage2. But the buildbots don't test stage1,
so now both dynamic and native tests are run during stage2.

Closes #13740.
rustdoc: refactor and unstyle inline section headers
syntax: ViewItemUse no longer contains multiple view paths.

it reflected the obsolete syntax `use a, b, c;` and did not make
past the parser (though it was a non-fatal error so we can continue).
this legacy affected many portions of rustc and rustdoc as well,
so this commit cleans them up altogether.
rustdoc: Moved `SCHEMA_VERSION` to `clean`.

it should be changed when the module gets updated, so it helps to
have the `SCHEMA_VERSION` with the definitions themselves.
auto merge of #13769 : alexcrichton/rust/restrict-some-scopes, r=huonw

This addresses the ICE from #13763, but it does not allow the test to compile,
due to #13768. An alternate test was checked in in the meantime.

Closes #13763
std: Add experimental networking methods

The underlying I/O objects implement a good deal of various options here and
there for tuning network sockets and how they perform. Most of this is a relic
of "whatever libuv provides", but these options are genuinely useful.

It is unclear at this time whether these options should be well supported or
not, or whether they have correct names or not. For now, I believe it's better
to expose the functionality than to not, but all new methods are added with
an #[experimental] annotation.