Let jt build work on Ruby 3

eregon · eregon · commit 1dffe02d8ed3 · 2021-02-09T17:49:08.000+01:00
diff --git a/tool/jt.rb b/tool/jt.rb
@@ -751,6 +751,7 @@ def truffle_version
   def mx(*args)
     super(*args)
   end
+  ruby2_keywords :mx if respond_to?(:ruby2_keywords, true)
 
   def launcher
     puts ruby_launcher
