Fix emacs indentation of multi-line match patterns

Aligns to the same column if the previous line ends in a single '|' (but
not a '||').
Emacs: stay at the correct position when indenting

When indenting a non-blank line, stay at the same cursor position
relative to the content after indenting.
Emacs: indent relative to enclosing block

This changes the indent to calculate positions relative to the enclosing
block (or braced/parenthesized expression), rather than by an absolute
nesting level within the whole file.  This allows things like this to
work:

    let x =
        match expr {
            Pattern => ...
        }

With the old method, only one level of nesting would be added within the
match braces, so "Pattern" would have ended up aligned with the match.

The other change is that multiple parens/braces on the same line only
increase the indent once.  This is a very common case for passing
closures/procs.  The absolute nesting method would do this:

    spawn(proc() {
            // Indented out two indent levels...
    })

whereas the code in this commit does this:

    spawn(proc() {
        // Indented out only one level...
    })
Fix typo in emacs ERT test
Closes #12386. Removed 'pub mod' doc-comments in std::io's mod.rs file. Added summary doc-comments to test.rs, util.rs and stdio.rs.
vim: Tweak how comment nesting works

Don't try to match line comments inside of a comment block. That makes
no sense and can highlight differently for people who override their
highlights.

Similarly, don't match a doc-comment inside of a comment block. It
shouldn't be highlighted differently unless it's actually a doc-comment
(and nested comments are obviously not doc comments).

Fixes #12307.
Remove references to guide-conditions

std::condition was removed in 454882dcb7fdb03867d695a88335e2d2c8f7561a
but there are still links to the guide. Removing them.
tutorial: clearer explanation of freezing.

- "Lending an immutable pointer" might be confusing. It was not discussed why borrowed pointers are immutable in the first place.
- Make it clear that the borrowed pointers are immutable even if the variable was declared with `mut`.
- Make it clear that we cannot even assign anything to the variable while its value is being borrowed.

tutorial: change "--" to an em-dash.

tutorial: change instances of "--" to em-dash.
Update LLVM

Upstream LLVM has changed slightly such that our PassWrapper.cpp no longer
comiles (travis errors). This updates the bundled LLVM to the latest nightly
which will hopefully fix the travis errors we're seeing.
auto merge of #12539 : gmjosack/rust/master, r=alexcrichton

std::condition was removed in 454882dcb7fdb03867d695a88335e2d2c8f7561a
but there are still links to the guide. Removing them.
std: Tweak stack overflow printing for robustness

The printing of the error message on stack overflow had two sometimes false
assumptions previously. The first is that a local task was always available (it
called Local::take) and the second is that it used println! instead of
manually writing.

The first assumption isn't necessarily true because while stack overflow will
likely only be detected in situations that a local task is available, it's not
guaranteed to always be in TLS. For example, during a println! call a task
may be blocking, causing it to be unavailable. By using Local::try_take(), we
can be resilient against these occurrences.

The second assumption could lead to odd behavior because the stdout logger can
be overwritten to run arbitrary code. Currently this should be possible, but the
utility is much diminished because a stack overflow translates to an abort()
instead of a failure.
auto merge of #12548 : alexcrichton/rust/up-llvm, r=huonw,brson

Upstream LLVM has changed slightly such that our PassWrapper.cpp no longer
comiles (travis errors). This updates the bundled LLVM to the latest nightly
which will hopefully fix the travis errors we're seeing.
auto merge of #12505 : alexcrichton/rust/fix-stack-overflow, r=brson

The printing of the error message on stack overflow had two sometimes false
assumptions previously. The first is that a local task was always available (it
called Local::take) and the second is that it used `println!` instead of
manually writing.

The first assumption isn't necessarily true because while stack overflow will
likely only be detected in situations that a local task is available, it's not
guaranteed to always be in TLS. For example, during a `println!` call a task
may be blocking, causing it to be unavailable. By using Local::try_take(), we
can be resilient against these occurrences.

The second assumption could lead to odd behavior because the stdout logger can
be overwritten to run arbitrary code. Currently this should be possible, but the
utility is much diminished because a stack overflow translates to an abort()
instead of a failure.
auto merge of #12547 : jagtalon/rust/jag/rust/tutorial-freezing, r=pnkfelix

- "Lending an immutable pointer" might be confusing. It was not discussed why borrowed pointers are immutable in the first place.
- Make it clear that the borrowed pointers are immutable even if the variable was declared with `mut`.
- Make it clear that we cannot even assign anything to the variable while its value is being borrowed.

tutorial: change "--" to an em-dash.

tutorial: change instances of "--" to em-dash.
Mark top level module as a crate in rustdoc, closes #12507
tutorial: Missing tildes around .notrust block

Adds a missing tilde to the end and the start of two .notrust blocks.
Rename a few typeck method-related structures to UpperCamelCase.
Replace callee_id with information stored in method_map.
auto merge of #12571 : eddyb/rust/kill-callee-id, r=nikomatsakis

Every method call and overloaded operator had a `callee_id` that was be used to store the method type and type substitutions, that information is now stored in the `method_map`, alongside the method's origin.
auto merge of #12570 : kyrias/rust/master, r=cmr

Adds a missing tilde to the end and the start of two .notrust blocks.