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
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.
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
auto merge of #13777 : lifthrasiir/rust/no-multi-viewitemuse, r=alexcrichton

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 PR cleans them up altogether.

As a side effect of cleanup, we now have `SCHEMA_VERSION` in `rustdoc::clean` (instead of the crate root), so it has a better chance to be updated when `rustdoc::clean` gets updated.
Fixing permutation of small lists, such that [], [x] -> [[]], [[x]], and updating size_hints.
Fixes #13734 and #13759.
test: Rename a test to bypass UAC on windows
auto merge of #13783 : wackywendell/rust/permfix, r=kballard

I filed bugs #13734 and #13759 recently, and then realized I could probably fix them myself. This does exactly that, with a couple additional modifications and additions to the test-suite to pick up on that.

I've never done this before, so please feel free to tell me all the things I'm doing wrong or could be doing better.
Fix link to hashmap.rs and json.rs in sample code FAQ
Added missing values in std::io::standard_error()
Fixed typo in std::iter
add BigUint subtraction underflow error message
auto merge of #13796 : ema-fox/rust/patch-1, r=kballard
auto merge of #13798 : aochagavia/rust/pr, r=alexcrichton
Rewrote documentation for parse_bytes and to_str_bytes in {int, uint}_macros.rs
auto merge of #13792 : jacob-hegna/rust/master, r=alexcrichton

Just modified the documentation for parse_bytes to make it more clear how the bytes were parsed (big endian) and to show an example of what it returned.  I also added documentation for the to_str_bytes which previously had no documentation (besides one stackoverflow post).