Add -Zbuild-std test

Author: daxpedda

tests/integrations/basic-bin/Cargo.stdout

@@ -3,8 +3,10 @@ running 0 tests
 
 test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished 
 
+Building dependencies ... ok
+tests/actual_tests/foomp.rs ... ok
 Building dependencies ... ok
 tests/actual_tests/foomp.rs ... ok
 
-test result: ok. 1 passed;
+test result: ok. 2 passed;
 

tests/integrations/basic-bin/tests/ui_tests.rs

@@ -28,8 +28,18 @@ fn main() -> ui_test::color_eyre::Result<()> {
     config.out_dir = tmp_dir.into();
     config.path_stderr_filter(tmp_dir, "$$TMP");
 
+    // try with build-std
+    let config_build_std = config.clone();
+    config.comment_defaults.base().set_custom(
+        "dependencies",
+        DependencyBuilder {
+            build_std: Some(String::new()),
+            ..DependencyBuilder::default()
+        },
+    );
+
     run_tests_generic(
-        vec![config],
+        vec![config, config_build_std],
         default_file_filter,
         default_per_file_config,
         // Avoid github actions, as these would end up showing up in `Cargo.stderr`