Remove ignored #[must_use] attributes from Clippy

The `#[must_use]` attribute has no effect when applied to methods in trait implementations.

Author: samueltardieu

src/tools/clippy/clippy_lints/src/infinite_iter.rs

@@ -94,7 +94,6 @@ impl Finiteness {
 }
 
 impl From<bool> for Finiteness {
- #[must_use]
  fn from(b: bool) -> Self {
  if b { Infinite } else { Finite }
  }

src/tools/clippy/clippy_utils/src/consts.rs

@@ -351,21 +351,18 @@ pub enum FullInt {
 }
 
 impl PartialEq for FullInt {
- #[must_use]
  fn eq(&self, other: &Self) -> bool {
  self.cmp(other) == Ordering::Equal
  }
 }
 
 impl PartialOrd for FullInt {
- #[must_use]
  fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
  Some(self.cmp(other))
  }
 }
 
 impl Ord for FullInt {
- #[must_use]
  fn cmp(&self, other: &Self) -> Ordering {
  use FullInt::{S, U};