Add option to build rosettax87 locally (#9)

Reviewed-on: #9

pkg/patching/patching_test.go

@@ -0,0 +1,15 @@
+package patching
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestBuildRosetta(t *testing.T) {
+	rp, lp, err := BuildRosetta()
+	if err != nil {
+		t.Error(err)
+	}
+	fmt.Println("exe path:", rp)
+	fmt.Println("lib path:", lp)
+}