Fix typos in unix/rwlock.rs
Fix typos in unix/rwlock.rs

GBGamer/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,graydon/rust,graydon/rust,graydon/rust,graydon/rust,GBGamer/rust,aidancully/rust,GBGamer/rust,aidancully/rust,aidancully/rust,graydon/rust,GBGamer/rust,graydon/rust,aidancully/rust