Do not ever cross-check bootstrap tools

Author: Kobzol

src/bootstrap/src/core/build_steps/check.rs

@@ -502,6 +502,13 @@ macro_rules! tool_check_step {
             fn make_run(run: RunConfig<'_>) {
                 let target = run.target;
                 let build_compiler = prepare_compiler_for_check(run.builder, target, $mode);
+
+                // It doesn't make sense to cross-check bootstrap tools
+                let target = match $mode {
+                    Mode::ToolBootstrap => run.builder.host_target,
+                    _ => target,
+                };
+
                 run.builder.ensure($name { target, build_compiler });
             }