Add Rust 1.30.0

[iohe]

Be gentle, still lerning how to do PR.
Add 1.30.0 support

[nastevens]

Build is currently broken - looks like the COPYRIGHT file upstream changed and our existing implementation is pretty naive: https://github.com/rust-embedded/meta-rust-bin/blob/master/build-new-version.sh#L180. Do you want to try and tackle the changes needed to the script to dynamically write the copyright MD5?

[iohe]

autocompute md5 for COPYRIGHT file, updated file for rustc and verified that it works.

[nastevens]

I just found out that Rust 1.30.1 is planned to be released today so we'd be bumping almost immediately. Do you have any objections to waiting for 1.30.1 and then using that?

[iohe]

Fine with me. As a newbie with github/git and PR, please let me know recommended steps (other than running the script with 1.30.1

[posborne]

Fine with me. As a newbie with github/git and PR, please let me know recommended steps (other than running the script with 1.30.1

If you have a project using the layer, that would be the other validation to perform. We don't currently have CI setup to automate that as part of this project so @nastevens and I can do that testing as well prior to merge.

[fredszaq]

Hi there!
I've got a fairly big rust project that needs rust 1.30 to compile and it compiled without any problems on an aarch64 target using this branch.
This looks ready to be merged

[posborne]

@fredszaq Thanks for testing and thanks @iohe for the contribution. Merging.