Fix wrong radius valve from 0.0 to 1.0 as above

Many many many people ask in #rust about this libraries, having an
explanatory reason will probably help a lot.

fixed a doc mistake in libcore/marker.mk

Properly sorted, Ł goes between L and M.

Tiny tiny nitpick that I just noticed after getting a new laptop ( 🍺 + 💻 = 👼 ) and thus needing to ./configure anew on Yosemite. 

It's weird to see a message that says you're on 10.9 if you're on 10.10, in a oh-i-wonder-what-else-is-wrong sort of sense-- easy fix with a `>=` since `gcc --version` on 10.10 with the newest xcode still says it's clang.

❤ 

I deleted one unneccessary 'the' and added the href for [bindings]

… compared

cc #24407 

Following paragraph says "we've used `*` which..." but code says "rand=\"0.3.0\""

Building with `--target=mipsel-unknown-linux-gnu` currently results in the following errors, fixed by this PR:

```
rustc: x86_64-unknown-linux-gnu/stage2/lib/rustlib/mipsel-unknown-linux-gnu/lib/libstd
/vol/rust/src/libstd/os/linux/raw.rs:76:21: 76:28 error: use of undeclared type name `c_ulong`
/vol/rust/src/libstd/os/linux/raw.rs:76         pub st_dev: c_ulong,
                                                            ^~~~~~~
/vol/rust/src/libstd/os/linux/raw.rs:83:22: 83:29 error: use of undeclared type name `c_ulong`
/vol/rust/src/libstd/os/linux/raw.rs:83         pub st_rdev: c_ulong,
                                                             ^~~~~~~
/vol/rust/src/libstd/sys/common/net2.rs:210:52: 210:70 error: unresolved name `libc::TCP_KEEPIDLE`
/vol/rust/src/libstd/sys/common/net2.rs:210         setsockopt(&self.inner, libc::IPPROTO_TCP, libc::TCP_KEEPIDLE,
```

If you have 0 references (`&T`) to a resource, presumably, you could have a mutable reference (`&mut T`). So this only start to make sense at having 1 reference to a resource.

Fix wrong radius valve from 0.0 to 1.0 as above

Many many many people ask in #rust about this libraries, having an
explanatory reason will probably help a lot.

Properly sorted, Ł goes between L and M.

If you have 0 references (`&T`) to a resource, presumably, you could
have a mutable reference (`&mut T`). So this only start to make sense
at having 1 reference to a resource.

* Remove the 2-suffix from some modules
* Remove some unused files
* Remove double-boxing for `ReentrantMutex`

Fix #25076.

r? @nikomatsakis 

10.10 is out, so it's weird to see a message that says you're on 10.9.
Change the message to be >=10.9.

Ideally this trait implementation would be unstable, requiring crates to opt-in
if they would like the functionality, but that's not currently how stability
works so the implementation needs to be removed entirely.

This may come back at a future date, but for now the conservative option is to
remove it.

[breaking-change]

My change in #24797 had a bug, described in that issue’s comments, and first discovered in issue #24918. This fixes it.

I tested this new `main.js` by changing the `main.js` content of [a rendered docs page](https://doc.rust-lang.org/std/option/) to this new content. The ‘[−]’ button worked again.

I am also including another related fix, because it would require manual merging if I made a separate pull request for it. The page-global ‘[−]’ button currently adds `#` to the end of the URL whenever it is clicked. I am changing its `href` from `#` to `javascript:void(0)` (the same as the `href` for section-specific ‘[−]’ links) to fix that.

Perform unsafe initialization up front and then only afterward the mutex is in
place do we initialize it.

This module has been removed for quite some time!

Now that `std::old_io` has been removed for quite some time the naming real
estate here has opened up to allow these modules to move back to their proper
names.

Guard against overflow in `codemap::span_to_lines`.

(Revised/expanded version of PR #24976)

Make `span_to_lines` to return a `Result`.

In `diagnostic`, catch `Err` from `span_to_lines` and print `"(unprintable span)"` instead.

----

There a number of recent issues that report the bug here.  See e.g. #24761 and #24954.

This change *might* fix them. However, that is *not* its main goal. The main goals are:

 1. Make it possible for callers to recover from an error here, and

 2. Insert a more conservative check, in that we are also checking that the files match up.

----

As a drive-by, fix #24997 , which was causing my attempts to `make check-stage1` on an `--enable-debug` build to fail.

Didn't realise 0.3.0 referred to all 0.3.x versions! Fixed my mistakes. Should have just updated the Cargo.toml now.

changed paragraphs with discussion of Cargo.lock file to agree with rand version 0.3.0 in the Cargo.tom file.

The last one (at least for the moment 😃).

r? @alexcrichton 

Following paragraph says "we've used `*` which..." but code says "rand=\"0.3.0\""

- Successful merges: #24576, #24966, #25052, #25131, #25137, #25138, #25139, #25141, #25142, #25144, #25146, #25148, #25154, #25156, #25160, #25173
- Failed merges: