Add armv5te-unknown-linux-musl target

[hberntsen]

This PR adds the armv5te-unknown-linux-musl target. The following steps should let you produce a fully statically linked binary now:

1. Running ./src/ci/docker/run.sh dist-armv5te-linux-musl
2. Changing the run.sh script to start bash instead of the build process and running the container

3. export USER=root
   export PATH=/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin:/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin:$PATH

4. Configuring Cargo

   [target.armv5te-unknown-linux-musl]
   linker = "arm-linux-gnueabi-gcc"

5. Building a project

   cargo new --bin hello
   cd hello
   cargo build --target=armv5te-unknown-linux-musl --release

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @alexcrichton (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

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[alexcrichton]

Thanks! Could the docker image here be moved to disabled because we're not gonna be running it on CI? Otherwise looks good to me!

[hberntsen]

@alexcrichton I'd like this target to be included in the tier 2 platform support like the armv5te-unknown-linux-gnueabi target. That target is built in the dist-various-1 container. I could add the musl one from this PR to that container if that suits you more. I could also add the new container to CI.

By the way, I noticed that in the target names both musl and musleabi is used, which one should I use for the target in this PR?

[nagisa]

musleabi for 32-bit ARMs should be used.

[alexcrichton]

Ah yeah adding to an existing container is best as it doesnt take up another builder with Travis, if that can be done then we can ship this yeah

[hberntsen]

@alexcrichton Thanks! I've applied the suggested changes

[alexcrichton]

@bors: r+

Thanks!

[bors]

📌 Commit 235af75 has been approved by alexcrichton

[bors]

⌛ Testing commit 235af75 with merge fc6b2c5...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: alexcrichton
Pushing fc6b2c5 to master...