Do not make `parse_one` public
Do not make `parse_one` public

`parse_one` was never supposed to be public and it uses a bunch of non-public
types as a parameters, so downstream crates wouldn't be able to call it anyways.

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