fix warnings (#318)

Author: rupeshkoushik07

src/lib.rs

@@ -1,4 +1,3 @@
-#![feature(lazy_cell)]
 #![feature(rustc_private)] //for private crate imports for tests
 #![feature(vec_into_raw_parts)]
 #![feature(thread_local)]

src/main.rs

@@ -1,4 +1,3 @@
-#![feature(lazy_cell)]
 #![feature(rustc_private)] //for private crate imports for tests
 #![feature(vec_into_raw_parts)]
 #![feature(duration_constants)]

src/tools/fs_utils.rs

@@ -1,4 +1,3 @@
-#![feature(lazy_cell)]
 #![feature(rustc_private)] //for private crate imports for tests
 #![feature(vec_into_raw_parts)]
 #![feature(duration_constants)]