3482: Fix regression from #3451 r=matklad a=edwin0cheng
There is a regression from #3451 such that the following code has failed to parse in raw item collecting phase:
```rust
macro_rules! with_std {
($($i:item)*) => ($(#[cfg(feature = "std")]$i)*)
}
with_std! {
mod macros;
mod others;
}
```
### Rationale
We always assume the last token of an statement will not end with a whitespace, which is true. It is because in parsing phase, we always emit `SyntaxNode` before any whitespace. Such that in various parts of RA code, we solely check the semi-colon by using `SyntaxNode::last_child_token() == ";"` .
However, in #3451, we insert some whitespaces between puncts such that we broke above assumption. This PR fixed this bug by make sure we don't add any whitespace if it is a semicolon.
Co-authored-by: Edwin Cheng <edwin0cheng@gmail.com>