This commit adds two unstable flags to `rustc`: `-Z pre-link-arg` and `-Z
pre-link-args`. These are the counterpart of the existing `-C link-arg{,s}`
flags and can be used to pass extra arguments at the *beginning* of the linker
invocation, before the Rust object files are passed.

This PR does two things:
* Triggers an error on GNU/Linux & Android when /proc/self/exe doesn't exist
* Handle the error properly

… hashing.

As requested in rust-lang#29370.

…enabled

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>

Introduce a new Installer object that hold a reference to all the
configured paths for installation

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>

ci: allows files to be shared by docker images

Change `src/ci/docker/run.sh` to allow files to be shared when building docker containers. For while, only android related shell scripts are shared. Others containers can be updated at any time.

sccache is installed last, as it is frequently updated this avoids the need to rebuilt the whole container.

add -Z pre-link-arg{,s} to rustc

This PR adds two unstable flags to `rustc`: `-Z pre-link-arg` and `-Z
pre-link-args`. These are the counterpart of the existing `-C link-arg{,s}`
flags and can be used to pass extra arguments at the *beginning* of the linker
invocation, before the Rust object files are passed.

I have [started] a discussion on the rust-embedded RFCs repo about settling on a
convention for passing extra arguments to the linker and there are two options
on discussion: `.cargo/config`'s `target.$T.rustflags` and custom target
specification files (`{pre,,post}-link-args` fields). However, to compare these
two options on equal footing this `-Z pre-link-arg` feature is required.

[started]: rust-embedded/wg#24

Therefore I'm requesting landing this `-Z pre-link-arg` flag as an experimental
feature to evaluate these two options.

cc @brson
r? @alexcrichton

…=nrc

Fix ICE on `include!(line!())` (regression)

Fixes rust-lang#41776.
r? @nrc

…r=steveklabnik

Add documentation for `ExitStatus`

As requested in rust-lang#29370. r? @steveklabnik

Improve the error management when /proc is not mounted

This PR does two things:
* Triggers an error on GNU/Linux & Android when /proc/self/exe doesn't exist
* Handle the error properly

rustbuild: install improvements

Install rust-analysis and rust-src to get in par with what we can get from rustup.
Allow bypassing the vendoring of dependencies. When we only build to install and not to redistribute dist tarballs, that part is not necessary, so avoid trying to install cargo-vendor.

misc doc improvements for std::env

fix typo in libstd/sync/mpsc/mod.rs docs

Fix regression introduced by jQuery removal

Fixes rust-lang#42078.
Follows rust-lang#41307.

r? @steveklabnik
cc @frewsxcv

…hes, r=eddyb

incr. comp.: Use more bits for DefPath hashes

Use 128 instead of 64 bits for DefPath hashes, like we do for everything else. Collision probability is unnecessarily high with 64 bits.

Also change the representation of `ich::Fingerprint` from `Fingerprint([u8; 16])` to `Fingerprint(u64, u64)` which is better for hashers like `FxHasher`.

…lexcrichton

Fix x.py

Fixes rust-lang#42085