Replace lazy_static! with once_cell::sync::Lazy

As per
276134eb93 (r37745873),
this allows us to avoid a macro call and get better autocompletion
within the declaration.

Cargo.toml

@@ -22,10 +22,10 @@ path = "src/lib.rs"
 
 [dependencies]
 clap = { version = "2.33.0", optional = true }
-lazy_static = "1.4.0"
 num-rational = "0.2.3"
 num-bigint = "0.2.6"
 num-traits = "0.2.11"
+once_cell = "1.3.1"
 
 [features]
 default = ["commandline"]

src/builtin/mod.rs

@@ -1,4 +1,4 @@
-use lazy_static::lazy_static;
+use once_cell::sync::Lazy;
 use std::collections::HashMap;
 
 use crate::args::CallArgs;
@@ -19,14 +19,12 @@ mod string;
 
 pub(crate) type Builtin = Box<dyn Fn(&mut CallArgs, &Scope) -> SassResult<Value> + Send + Sync>;
 
-lazy_static! {
-    pub(crate) static ref GLOBAL_FUNCTIONS: HashMap<String, Builtin> = {
-        let mut m = HashMap::new();
-        color::register(&mut m);
-        list::register(&mut m);
-        math::register(&mut m);
-        meta::register(&mut m);
-        string::register(&mut m);
-        m
-    };
-}
+pub(crate) static GLOBAL_FUNCTIONS: Lazy<HashMap<String, Builtin>> = Lazy::new(|| {
+    let mut m = HashMap::new();
+    color::register(&mut m);
+    list::register(&mut m);
+    math::register(&mut m);
+    meta::register(&mut m);
+    string::register(&mut m);
+    m
+});