Remove the lazy_static dependency from rustbuild

Rustbuild already depends on once_cell which in the future can be
replaced with std::lazy::Lazy.

Cargo.lock

@@ -175,7 +175,6 @@ dependencies = [
  "filetime",
  "getopts",
  "ignore",
- "lazy_static",
  "libc",
  "merge",
  "num_cpus",

src/bootstrap/Cargo.toml

@@ -44,7 +44,6 @@ libc = "0.2"
 serde = { version = "1.0.8", features = ["derive"] }
 serde_json = "1.0.2"
 toml = "0.5"
-lazy_static = "1.3.0"
 time = "0.1"
 ignore = "0.4.10"
 opener = "0.5"

src/bootstrap/cache.rs

@@ -13,7 +13,8 @@
 use std::path::{Path, PathBuf};
 use std::sync::Mutex;
 
-use lazy_static::lazy_static;
+// FIXME: replace with std::lazy after it gets stabilized and reaches beta
+use once_cell::sync::Lazy;
 
 use crate::builder::Step;
 
@@ -222,9 +223,7 @@ pub fn intern_path(&self, s: PathBuf) -> Interned<PathBuf> {
     }
 }
 
-lazy_static! {
-    pub static ref INTERNER: Interner = Interner::default();
-}
+pub static INTERNER: Lazy<Interner> = Lazy::new(Interner::default);
 
 /// This is essentially a `HashMap` which allows storing any type in its input and
 /// any type in its output. It is a write-once cache; values are never evicted,