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.
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.
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.
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.
rustc: Explicitly mention type params with missing `'static` bounds

Also renames `check_durable` to `check_static` and removes the outdated
comment.
rustc: Get rustc compiling with LLVM 3.{3,4} again

The travis builds have been breaking recently because LLVM 3.5 upstream is
changing. This looks like it's likely to continue, so it would be more useful
for us if we could lock ourselves to a system LLVM version that is not changing.

This commit has the support to bring our C++ glue to LLVM back in line with what
was possible back in LLVM 3.{3,4}. I don't think we're going to be able to
reasonably protect against regressions in the future, but this kind of code is a
good sign that we can continue to use the system LLVM for simple-ish things.
Codegen for ARM won't work and it won't have some of the perf improvements we
have, but using the system LLVM should work well enough for development.
travis: Use LLVM 3.3 from the official repos

We can be certain that this version of LLVM will not be changing, so we don't
have to worry about API drift over time.
Fix a pretty printer crash on `/***`.

The pretty printer was treating block comments with more than two
asterisks after the first slash (e.g. `/***`) as doc comments (which are
attributes), whereas in actual fact they are just regular comments.
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.