Add cross-compilation tool test

Author: Kobzol

src/bootstrap/src/core/builder/tests.rs

@@ -780,6 +780,35 @@ mod snapshot {
         );
     }
 
+    #[test]
+    fn build_compiler_tools_cross() {
+        let ctx = TestCtx::new();
+        insta::assert_snapshot!(
+            ctx
+                .config("build")
+                .stage(2)
+                .args(&["--set", "rust.lld=true", "--set", "rust.llvm-bitcode-linker=true"])
+                .hosts(&[TEST_TRIPLE_1])
+                .render_steps(), @r"
+        [build] llvm <host>
+        [build] rustc 0 <host> -> rustc 1 <host>
+        [build] rustc 0 <host> -> LldWrapper 1 <host>
+        [build] rustc 1 <host> -> LlvmBitcodeLinker 2 <host>
+        [build] rustc 1 <host> -> std 1 <host>
+        [build] rustc 1 <host> -> rustc 2 <host>
+        [build] rustc 1 <host> -> LldWrapper 2 <host>
+        [build] rustc 2 <host> -> LlvmBitcodeLinker 3 <host>
+        [build] rustc 1 <host> -> std 1 <target1>
+        [build] rustc 2 <host> -> std 2 <target1>
+        [build] llvm <target1>
+        [build] rustc 1 <host> -> rustc 2 <target1>
+        [build] rustc 1 <host> -> LldWrapper 2 <target1>
+        [build] rustc 2 <target1> -> LlvmBitcodeLinker 3 <target1>
+        [build] rustdoc 1 <target1>
+        "
+        );
+    }
+
     #[test]
     fn build_library_no_explicit_stage() {
         let ctx = TestCtx::new();