[Truffle] JT: alias "jt ruby" to "jt run".

* So we can just prepend jt to switch from another ruby.

Author: eregon

tool/jt.rb

@@ -230,6 +230,7 @@ def run(*args)
 
     raw_sh(env_vars, "#{JRUBY_DIR}/bin/jruby", *jruby_args, *args)
   end
+  alias ruby run
 
   def test(*args)
     return test_pe if args == ['pe']