Auto merge of #118138 - Nilstrieb:one-previous-error, r=WaffleLapkin

Fixes error count display is different when there's only one error left

Supersedes #114759

### What did I do?

I did the small change in `rustc_errors` by hand. Then I did the other changes in `/compiler` by hand, those were just find replace on `*.rs` in the workspace. The changes in run-make are find replace for `run-make` in the workspace.

All other changes are blessed using `x test TEST --bless`. I blessed the tests that were blessed in #114759.

### how to review this nightmare

ping bors with an `r+`. You should check that my logic is sound and maybe quickly scroll through the diff, but fully verifying it seems fairly hard to impossible. I did my best to do this correctly.

Thank you `@adrianEffe` for bringing this up and your initial implementation.

cc `@flip1995,` you said you want to do a subtree sync asap
cc `@RalfJung` maybe you want to do a quick subtree sync afterwards as well for Miri

r? `@WaffleLapkin`

1 files changed, 1 insertions, 1 deletions

diff --git a/tests/ui/structs/struct-missing-comma.stderr b/tests/ui/structs/struct-missing-comma.stderr
index eceec65e763..4fdd47a4806 100644
--- a/tests/ui/structs/struct-missing-comma.stderr
+++ b/tests/ui/structs/struct-missing-comma.stderr
@@ -4,5 +4,5 @@ error: expected `,`, or `}`, found keyword `pub`
 LL |     pub foo: u32
    |                 ^ help: try adding a comma: `,`
 
-error: aborting due to previous error
+error: aborting due to 1 previous error