Add typo suggestion for a misspelt Cargo environment variable

[chenyukang]

Fixes #148439

[rustbot]

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[jieyouxu]

Discussion (non-blocking): I have two reservations about making this suggestion:

1. Wouldn't this depend on the specific cargo version?
2. Basically, what I was trying to get at, is that in principle I feel like rustc should not make assumptions about cargo (that is, rustc should not "know" about cargo's existence), because cargo isn't the only way to invoke rustc.

I guess I could be convinced by "well, most users do build with cargo", so don't consider this a hard-blocking concern.

[chenyukang]

1. I'm not sure, there is a similar list for this in rust-analyzer: https://github.com/chenyukang/rust/blob/702bf000a0b5062d8b5ced717a26d70919df6ba0/src/tools/rust-analyzer/crates/project-model/src/env.rs#L9-L49 , I guess there is a better and general way to keep it synced.
2. I agree rustc should not knowing details about cargo, I think it's ok since we need to check the prefix with CARGO_ of env:
   https://github.com/rust-lang/rust/pull/148559/files#diff-0eaa1095d59f2f3d9c015005d15fd8f7cda13121a8404d77b2955fc5fcd40449R213, and it's a note but not code suggestions, it's maybe incorrect for rare scenarios.

[jieyouxu]

Yeah, seems alright, was just curious to hear what you think.

[Kivooeo]

Some nits

View changes since this review

[Kivooeo]

@bors r+

[bors]

📌 Commit 3edd25f has been approved by Kivooeo

It is now in the queue for this repository.