resolve llvm-config path properly on cross builds

Signed-off-by: onur-ozkan <work@onurozkan.dev>

Author: onur-ozkan

src/bootstrap/src/core/build_steps/llvm.rs

@@ -120,9 +120,14 @@ pub fn prebuilt_llvm_config(
     let root = "src/llvm-project/llvm";
     let out_dir = builder.llvm_out(target);
 
-    let mut llvm_config_ret_dir = builder.llvm_out(builder.config.build);
-    llvm_config_ret_dir.push("bin");
-    let build_llvm_config = llvm_config_ret_dir.join(exe("llvm-config", builder.config.build));
+    let build_llvm_config = if target == builder.config.build {
+        let mut llvm_config_ret_dir = builder.llvm_out(builder.config.build);
+        llvm_config_ret_dir.push("bin");
+        llvm_config_ret_dir.join(exe("llvm-config", builder.config.build))
+    } else {
+        builder.ensure(Llvm { target: builder.config.build }).llvm_config
+    };
+
     let llvm_cmake_dir = out_dir.join("lib/cmake/llvm");
     let res = LlvmResult { llvm_config: build_llvm_config, llvm_cmake_dir };