Remove #[macro_use] extern crate tracing from rustc_resolve.

Explicit imports are more standard nowadays and easier to read.

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -40,6 +40,7 @@ use std::iter;
 use std::ops::Deref;
 
 use thin_vec::ThinVec;
+use tracing::debug;
 
 use super::NoConstantGenericsReason;