Expose `target_abi = "v8plus"` on sparc-unknown-linux-gnu

[RalfJung]

Proposal

(Disclaimer: I am not a SPARC expert, this is my summary based om what I learned in rust-lang/rust#157083 and rust-lang/rust#160562.)

32bit SPARC has (at least) two different ABIs: V8 (used by default by LLVM) and V8+. In such a situation we usually distinguish the ABI by setting target_abi (so the user can cfg on it should that be needed). So I propose we add a new possible value to target_abi: "v8plus" to indicate V8+. We could possibly also add "v8" for the standard V8 ABI, if we want to not leave this as an implicit default.

Cc @taiki-e @jonathanpallant

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cc @rust-lang/compiler

[tgross35]

@rustbot second

[rustbot]

The final comment period is now complete, this major change is now accepted. 🎉

As the automated representative, I want to express gratitude to the author for their work and everyone else who contributed to this major change proposal.

If you think this major change shouldn't have been accepted, feel free to remove the major-change-accepted label and reopen this issue.

Note

Further progress is now tracked over at rust-lang/rust#161835.