De-pub some private runtime components

This change was waiting for privacy to get sorted out, which should be true now
that #8215 has landed.

Closes #4427
extra::tempfile: replace mkdtemp with an RAII wrapper

this incidentally stops `make check` from leaving directories in `/tmp`
auto merge of #9802 : ben0x539/rust/mkdtemp-raii, r=alexcrichton

this incidentally stops `make check` from leaving directories in `/tmp` (Closes #9764)
auto merge of #9803 : alexcrichton/rust/less-pub2, r=brson

This change was waiting for privacy to get sorted out, which should be true now
that #8215 has landed.

Closes #4427
correct names for `#[no_send]`/`#[no_freeze]` tests
Remove support for older CrateMap versions
clean up the `Rc`/`RcMut` types and move to libstd
auto merge of #9794 : thestinger/rust/rc, r=alexcrichton

I've left out a way to construct from a `Send` type until #9509 is resolved. I am confident that this interface can remain backwards compatible though, assuming we name the `Pointer` trait method `borrow`.

When there is a way to convert from `Send` (`from_send`), a future RAII-based `Mut` type can be used with this to implemented a mutable reference-counted pointer. For now, I've left around the `RcMut` type but it may drastically change or be removed.
auto merge of #9809 : fhahn/rust/remove-old-cratemap-code, r=alexcrichton

This patch removes the code responsible for handling older CrateMap versions (as discussed during #9593). Only the new (safer) layout is supported now.