pig-latin example: Use lazy_static 1.4.0 (#881)
pig-latin example: Use lazy_static 1.4.0 (#881)

Otherwise, ONCE_INIT deprecated in Rust 1.38.0.
https://travis-ci.org/exercism/rust/jobs/590089919

Need 1.4.0 with this commit:
https://github.com/rust-lang-nursery/lazy-static.rs/commit/1dbd5ae6ccb33c1f88fe521c9ab1f8f0e4cf5193
petertseng/exercism-rust,petertseng/exercism-rust,petertseng/exercism-rust,exercism/xrust,exercism/xrust