Auto merge of #41174 - estebank:issue-41155, r=nikomatsakis

Point at only one char on `Span::next_point`

Avoid pointing at two chars so the diagnostic output doesn't display a
multiline span when starting beyond a line end.

Fix #41155.

Instead of

```rust
error: expected one of `(`, `const`, `default`, `extern`, `fn`, `type`, or `unsafe`, found `}`
 --> <anon>:3:1
  |
1 |   impl S {	pub
  |  _____________- starting here...
2 | |
  | |  ...ending here: expected one of 7 possible tokens here
3 |   }
  |   ^ unexpected token
```

show

```rust
error: expected one of `(`, `const`, `default`, `extern`, `fn`, `type`, or `unsafe`, found `}`
  --> <anon>:13:1
   |
12 |     pub
   |        - expected one of 7 possible tokens here
13 | }
   | ^ unexpected token
```

0 files changed, 0 insertions, 0 deletions