Rollup merge of rust-lang#119171 - nnethercote:cleanup-errors-4, r=compiler-errors

Cleanup error handlers: round 4

More `rustc_errors` cleanups. A sequel to rust-lang#118933.

r? `@compiler-errors`

Author: compiler-errors

src/base.rs

@@ -179,7 +179,7 @@ pub(crate) fn compile_fn(
                 let early_dcx = rustc_session::EarlyDiagCtxt::new(
                     rustc_session::config::ErrorOutputType::default(),
                 );
-                early_dcx.early_error(format!(
+                early_dcx.early_fatal(format!(
                     "backend implementation limit exceeded while compiling {name}",
                     name = codegened_func.symbol_name
                 ));