Fix flag parsing

PiperOrigin-RevId: 232470483
diff --git a/tools/migration/convert_crosstool_to_starlark.go b/tools/migration/convert_crosstool_to_starlark.go
index ddd64ca..799ef32 100644
--- a/tools/migration/convert_crosstool_to_starlark.go
+++ b/tools/migration/convert_crosstool_to_starlark.go
@@ -33,6 +33,7 @@
 )
 
 func main() {
+	flag.Parse()
 
 	if *crosstoolLocation == "" {
 		log.Fatalf("Missing mandatory argument 'crosstool'")