Construct DiagCtxt a bit earlier in build_session

compiler/rustc_interface/src/interface.rs

@@ -442,7 +442,6 @@ pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Se
             locale_resources.push(codegen_backend.locale_resource());
 
             let mut sess = rustc_session::build_session(
-                early_dcx,
                 config.opts,
                 CompilerIO {
                     input: config.input,

compiler/rustc_interface/src/tests.rs

@@ -65,7 +65,6 @@ where
         static USING_INTERNAL_FEATURES: AtomicBool = AtomicBool::new(false);
 
         let sess = build_session(
-            early_dcx,
             sessopts,
             io,
             None,