mips64-unknown-linux-gnuabi64 for Rust 1.72 is missing in rustup

[eduardosm]

mips64-unknown-linux-gnuabi64 target for Rust 1.72 is missing in rustup, producing the following error while trying to update:

error: component 'rust-std' for target 'mips64-unknown-linux-gnuabi64' is unavailable for download for channel 'stable'
error: If you don't need the component, you could try a minimal installation with:
error: 
error:     rustup toolchain add stable --profile minimal

This target is listed as tier 2, was available in Rust 1.71 and it is not mentioned in Rust 1.72 release notes as being downgraded.

[Urgau]

It was decided the downgrade them to Tier 3 in rust-lang/compiler-team#648

The documentation should have been updated but unfortunately it seems to have been forgotten. If you want to update it it should be in src/doc/rustc/src/platform-support.md.

@rustbot label -needs-triage +O-mips +A-docs
cc @workingjubilee (as the MCP and PR author)

[CryZe]

The release notes probably should be updated too.

[workingjubilee]

Apologies, I had been told that the intent was to run the standard library build on the release day-of until it was formally downgraded and did not realize that was with an "only once" clause, so it fell through the cracks amongst other recent excitement.

[eduardosm]

I will open a PR to fix the platform support documentation. I will not do anything with release notes because I'm not sure how that should be handled.

EDIT: Nevermind, I just found about #115238