Only compute which types we can derive PartialEq for if we'll use it
Only compute which types we can derive PartialEq for if we'll use it

If we aren't going to derive `PartialEq`, then it doesn't make sense to even run
the analysis.

emilio/rust-bindgen,rust-lang/rust-bindgen,rust-lang/rust-bindgen,rust-lang/rust-bindgen,rust-lang/rust-bindgen,emilio/rust-bindgen,emilio/rust-bindgen,emilio/rust-bindgen,emilio/rust-bindgen