Always import all tracing macros for the entire crate instead of piecemeal by module

compiler/rustc_ast_passes/src/lib.rs

@@ -12,6 +12,9 @@
 #![feature(let_else)]
 #![recursion_limit = "256"]
 
+#[macro_use]
+extern crate tracing;
+
 pub mod ast_validation;
 mod errors;
 pub mod feature_gate;