Replace lazy_static with once_cell

Cargo.toml

@@ -19,7 +19,7 @@ alpn = ["security-framework/alpn"]
 [target.'cfg(any(target_os = "macos", target_os = "ios"))'.dependencies]
 security-framework = "2.0.0"
 security-framework-sys = "2.0.0"
-lazy_static = "1.4.0"
+once_cell = "1.0.0"
 libc = "0.2"
 tempfile = "3.1.0"
 

src/imp/security_framework.rs

@@ -1,4 +1,5 @@
 extern crate libc;
+extern crate once_cell;
 extern crate security_framework;
 extern crate security_framework_sys;
 extern crate tempfile;
@@ -20,6 +21,8 @@ use std::str;
 use std::sync::Mutex;
 use std::sync::Once;
 
+#[cfg(not(target_os = "ios"))]
+use self::once_cell::Lazy;
 #[cfg(not(target_os = "ios"))]
 use self::security_framework::os::macos::certificate::{PropertyType, SecCertificateExt};
 #[cfg(not(target_os = "ios"))]
@@ -38,9 +41,7 @@ use {Protocol, TlsAcceptorBuilder, TlsConnectorBuilder};
 static SET_AT_EXIT: Once = Once::new();
 
 #[cfg(not(target_os = "ios"))]
-lazy_static! {
-    static ref TEMP_KEYCHAIN: Mutex<Option<(SecKeychain, TempDir)>> = Mutex::new(None);
-}
+static TEMP_KEYCHAIN: Lazy<Mutex<Option<(SecKeychain, TempDir)>>> = Lazy::new(|| Mutex::new(None));
 
 fn convert_protocol(protocol: Protocol) -> SslProtocol {
     match protocol {

src/lib.rs

@@ -98,10 +98,6 @@
 #![warn(missing_docs)]
 #![cfg_attr(docsrs, feature(doc_cfg))]
 
-#[macro_use]
-#[cfg(any(target_os = "macos", target_os = "ios"))]
-extern crate lazy_static;
-
 use std::any::Any;
 use std::error;
 use std::fmt;