clippy 0.0.208

A bunch of helpful lints to avoid common pitfalls in Rust
error: Negation by multiplying with -1
  --> $DIR/neg_multiply.rs:30:5
   |
30 |     x * -1;
   |     ^^^^^^
   |
   = note: `-D neg-multiply` implied by `-D warnings`

error: Negation by multiplying with -1
  --> $DIR/neg_multiply.rs:32:5
   |
32 |     -1 * x;
   |     ^^^^^^

error: aborting due to 2 previous errors