rustc: Disable rpath settings by default

This commit disables rustc's emission of rpath attributes into dynamic libraries
and executables by default. The functionality is still preserved, but it must
now be manually enabled via a `-C rpath` flag.

This involved a few changes to the local build system:

* --disable-rpath is now the default configure option
* Makefiles now prefer our own LD_LIBRARY_PATH over the user's LD_LIBRARY_PATH
  in order to support building rust with rust already installed.
* The compiletest program was taught to correctly pass through the aux dir as a
  component of LD_LIBRARY_PATH in more situations.

The major impact of this change is that neither rustdoc nor rustc will work
out-of-the-box in all situations because they are dynamically linked. It must be
arranged to ensure that the libraries of a rust installation are part of the
LD_LIBRARY_PATH. The default installation paths for all platforms ensure this,
but if an installation is in a nonstandard location, then configuration may be
necessary.

Additionally, for all developers of rustc, it will no longer be possible to run
$target/stageN/bin/rustc out-of-the-box. The old behavior can be regained
through the `--enable-rpath` option to the configure script.

This change brings linux/mac installations in line with windows installations
where rpath is not possible.

Closes #11747
[breaking-change]
Updated release notes for 0.11.0
Update AUTHORS.txt
Update to 0.11.0
librustc: Allow coercions through arrays.
std: make sure HashMap from_iter uses random initialization by default

It turns out that HashMap's from_iter implementation was being
initialized without the sip keys being randomized. This adds
a custom default hasher that should avoid this potential vulnerability.
std: micro optimize Hash{Map,Set}::{new,with_capacity}
Updated release notes for 0.11.0
Vim syntax file types and traits cleanup
relicense shootout-mandelbrot.rs

Part of #14248

Main authors:
- @Ryman: OK
- @TeXitoi: OK
- @pcwalton: OK

Minor authors:
- @brson: OK
- @alexcrichton: OK
- @kballard: OK

Remark: @tedhorst was a main contributor, but its contribution
disapear with @pcwalton rewrite at af4ea11
std: move the hash docstring over to std::hash.
Add examples for from_utf8_owned, from_char, from_chars, from_byte
auto merge of #15301 : jasonthompson/rust/docs/str2, r=alexcrichton
Re-arrange TOC.

I'm going to move testing to be right AFTER the guessing game. I wanted it
to be borderline TDD, but I think that, since the first example is just one
file, it might be a bit overkill.

I'm doing this in its own commit to hopefully avoid merge conflicts.
Improve rustdocs for Rc, add examples
doc: Clarify that an error is a compiler error

This was asked on HN, and it's easy to clarify.
auto merge of #15308 : brson/rust/intro, r=alexcrichton

This was asked on HN, and it's easy to clarify.
test: Add tests for issue #12223, "drop allowed while active borrows
still in scope".

This issue was fixed by PR #12828 and #5781. All that was left was to
add tests.

Closes #12223.
auto merge of #15251 : AlisdairO/rust/master, r=alexcrichton

I've seen quite a bit of confusion around regarding the use of Rc, so I thought I'd take a stab at adding some examples.
auto merge of #15292 : alxgnon/rust/vim_syntax_cleanup, r=cmr

- Fix a couple mistakes:
  - `Ordering` is an enum, not a trait.
  - `Container` is now named `Collection`.
  - Add missing `CheckedDiv`.
  - Remove obsolete `OwnedVector`.
- Reorganize some lines to match [prelude's arrangement](http://doc.rust-lang.org/std/prelude/#reexports), making mistakes easier to spot in the future.