Remove extern crate tracing from numerous crates.

compiler/rustc_transmute/src/layout/dfa.rs

@@ -2,6 +2,7 @@ use super::{nfa, Byte, Nfa, Ref};
 use crate::Map;
 use std::fmt;
 use std::sync::atomic::{AtomicU32, Ordering};
+use tracing::instrument;
 
 #[derive(PartialEq, Clone, Debug)]
 pub(crate) struct Dfa<R>

compiler/rustc_transmute/src/lib.rs

@@ -2,9 +2,6 @@
 #![feature(never_type)]
 #![allow(unused_variables)]
 
-#[macro_use]
-extern crate tracing;
-
 pub(crate) use rustc_data_structures::fx::{FxIndexMap as Map, FxIndexSet as Set};
 
 pub mod layout;

compiler/rustc_transmute/src/maybe_transmutable/mod.rs

@@ -1,3 +1,5 @@
+use tracing::{debug, instrument, trace};
+
 pub(crate) mod query_context;
 #[cfg(test)]
 mod tests;