Make `suspicious_arithmetic_impl` understand multiplicative inverses

[Raph Levien]

Summary

I pretty often write Div impls that multiply by a reciprocal, as that's more efficient, and for graphics operations, giving up precise rounding behavior is usually not a problem. When working on the color crate, it was one of the few exceptions I had to ask for.

I suggest we recognize the * rhs.recip() idiom and accept it as a valid alternative to division.

Lint Name

suspicious_arithmetic_impl

Reproducer

I tried this code:

impl<T: Colorspace> core::ops::Div<f32> for PremulColor<T> {
    type Output = Self;

    fn div(self, rhs: f32) -> Self {
        self * rhs.recip()
    }
}

I saw this happen:

warning: suspicious use of `*` in `Div` impl
   --> color/src/color.rs:451:14
    |
451 |         self * rhs.recip()
    |              ^
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#suspicious_arithmetic_impl
    = note: `#[warn(clippy::suspicious_arithmetic_impl)]` on by default```

I expected to see this happen:

No lint.

### Version

rustc 1.82.0 (f6e511eec 2024-10-15)
binary: rustc
commit-hash: f6e511eec7342f59a25f7c0534f1dbea00d01b14
commit-date: 2024-10-15
host: aarch64-apple-darwin
release: 1.82.0
LLVM version: 19.1.1


### Additional Labels

_No response_