ensure std for cross-targets

Previously, doing `x test compiler/*` would fail the build due to missing std.
This change ensures that it is prepared.

Signed-off-by: onur-ozkan <[email protected]>

Author: onur-ozkan

src/bootstrap/src/core/build_steps/test.rs

@@ -2567,6 +2567,10 @@ impl Step for Crate {
         builder.ensure(compile::Std::force_recompile(compiler, target));
         builder.ensure(RemoteCopyLibs { compiler, target });
 
+        if builder.config.build != target {
+            builder.ensure(compile::Std::force_recompile(compiler, compiler.host));
+        }
+
         // If we're not doing a full bootstrap but we're testing a stage2
         // version of libstd, then what we're actually testing is the libstd
         // produced in stage1. Reflect that here by updating the compiler that