Also spell out that read and write operations should be retried on
`ErrorKind::Interrupted` errors.

Fixes rust-lang#38494.

Fixes rust-lang#37866

Previously the `cargotest` suite would run some arbitrary revision of Cargo's
test suite, but now that we're bundling it in tree we should be running the
Cargo submodule's test suite instead.

Suppress warning introduced by rust-lang/cargo#3841.

ASan and TSan are supported on macOS, and this commit enables their
support.

The sanitizers are always built as *.dylib on Apple platforms, so they
cannot be statically linked into the corresponding `rustc_?san.rlib`. The
dylibs are directly copied to `lib/rustlib/x86_64-apple-darwin/lib/`
instead.

Note, although Xcode also ships with their own copies of ASan/TSan dylibs,
we cannot use them due to version mismatch.

There is a caveat: the sanitizer libraries are linked as @rpath, so the
user needs to additionally pass `-C rpath`:

    rustc -Z sanitizer=address -C rpath file.rs
                               ^~~~~~~~

Otherwise there will be a runtime error:

    dyld: Library not loaded: @rpath/libclang_rt.asan_osx_dynamic.dylib
      Referenced from: /path/to/executable
      Reason: image not found
    Abort trap: 6

The next commit includes a temporary change in compiler to force the linker
to emit a usable @rpath.

Fixes rust-lang#41514.

Resolves rust-lang#29067.

Adds rust-windbg.cmd script

Adds rust-gdb/rust-lldb equivalent for windbg that loads the Rust .natvis files on start.

This change modifies the bootstrap code to add rust-windbg to bin and the .natvis files to lib/rustlib/etc.

Example usage from cmd or PowerShell:
```
rust-windbg -c "bu rs_f442289d74765418!rs::main;g" target\debug\rs.exe
```

Implement Vec::splice and String::splice (RFC 1432)

RFC: rust-lang/rfcs#1432, tracking issue: rust-lang#32310
A rebase of rust-lang#32355 with a few more tests.

Let me know if you have any ideas for more tests.

cc @SimonSapin

…chton

Support AddressSanitizer and ThreadSanitizer on x86_64-apple-darwin

[ASan](https://clang.llvm.org/docs/AddressSanitizer.html#supported-platforms) and [TSan](https://clang.llvm.org/docs/ThreadSanitizer.html#supported-platforms) are supported on macOS, and this commit enables their support.

The sanitizers are always built as `*.dylib` on Apple platforms, so they cannot be statically linked into the corresponding `rustc_?san.rlib`. The dylibs are directly copied to `lib/rustlib/x86_64-apple-darwin/lib/` instead.

Note, although Xcode also ships with their own copies of ASan/TSan dylibs, we cannot use them due to version mismatch.

----

~~There is a caveat: the sanitizer libraries are linked as `@rpath/` (due to https://reviews.llvm.org/D6018), so the user needs to additionally pass `-C rpath`:~~

**Edit:** Passing rpath is now automatic.

Run tests for the cargo submodule in tree

Previously the `cargotest` suite would run some arbitrary revision of Cargo's
test suite, but now that we're bundling it in tree we should be running the
Cargo submodule's test suite instead.

…richton

Add bootstrap support for android

Specify behavior of `write_all` for `ErrorKind::Interrupted` errors

Also spell out that read and write operations should be retried on
`ErrorKind::Interrupted` errors.

Fixes rust-lang#38494.