Fix `Vec::map_in_place` not doing what is written in the comment
Fix for issue #17574
Look for standard crates in LIBDIR provided by --libdir option,
not in hardcoded libdir path. If there was no LIBDIR provided
during configuration fallback to hardcoded paths.

Thanks to Jan Niklas Hasse for solution and to Alex Crichton for improvements.

Closes #11671
Conformed the 100 char limit and changed colon to semicolon
Require that objects can only be made from Sized types. Fixes #18333.
Rename remaining Failures to Panic
Link std::str to reference literals section
auto merge of #18750 : nikomatsakis/rust/issue-18333-skolemize-open-existential, r=nrc

In the general case, at least, it is not possible to make an object out of an unsized type. This is because the object type would have to store the fat pointer information for the `self` value *and* the vtable -- meaning it'd have to be a fat pointer with three words -- but for the compiler to know that the object requires three words, it would have to know the self-type of the object (is `self` a thin or fat pointer?), which of course it doesn't.

Fixes #18333.

r? @nick29581
Add examples for all literal types in reference grouped together
auto merge of #18773 : subhashb/rust/convert_remaining_failures_to_panic, r=steveklabnik

I have also renamed `fail` to `panic` in some non-documentation comments, where I thought it mattered.
Fixes #18677 

cc @steveklabnik
auto merge of #18441 : mdinger/rust/literals, r=steveklabnik

Closes #18415

This links [`std::str`](http://doc.rust-lang.org/std/str/index.html) documentation to [literals](http://doc.rust-lang.org/reference.html#literals) in the reference guide and collects examples of literals into one group at the beginning of the section. ~~The new tables are not exhaustive (some escapes were skipped) and so I try to link back to the respective sections where more detail is located.~~ The tables are are mostly exhaustive. I misunderstood some of the whitespace codes.

I don't think the tables actually look that nice if that's important and I'm not sure how it could be improved. I think it does do a good job of collecting available options together. I think listing the escapes together is particularly helpful because they vary with type and are embedded in paragraphs.

[EDIT]
The [ascii table](http://man-ascii.com/) is here and may be useful.
Remove Runtime trait

This commit removes most of the remaining runtime infrastructure related
to the green/native split. In particular, it removes the `Runtime` trait
and instead inlines the native implementation.

Closes #17325

[breaking-change]
Remove libnative

With runtime removal complete, there's nothing left of libnative. This
commit removes it.

Fixes #18687

[breaking-change]
Remove libgreen

With runtime removal complete, there is no longer any reason to provide
libgreen.

[breaking-change]
Rewrite sync::mutex as thin layer over native mutexes

Previously, sync::mutex had to split between green and native runtime
systems and thus could not simply use the native mutex facility.

This commit rewrites sync::mutex to link directly to native mutexes; in
the future, the two will probably be coalesced into a single
module (once librustrt is pulled into libstd wholesale).
Fallout from libgreen and libnative removal
Make most of std::rt private

Previously, the entire runtime API surface was publicly exposed, but
that is neither necessary nor desirable. This commit hides most of the
module, using librustrt directly as needed. The arrangement will need to
be revisited when rustrt is pulled into std.

[breaking-change]
Fallout from new termination semantics
Fallout from namespaced enums
Loosen possibly bogus constraints in backtrace test