Use the Rubinius thread-safe array and hash on Truffle.

Author: chrisseaton

lib/concurrent/array.rb

@@ -25,7 +25,7 @@ class Array < ::Array
       include JRuby::Synchronized
     end
 
-  elsif Concurrent.on_rbx?
+  elsif Concurrent.on_rbx? || Concurrent.on_truffle?
     require 'monitor'
     require 'concurrent/thread_safe/util/array_hash_rbx'
 

lib/concurrent/hash.rb

@@ -22,7 +22,7 @@ class Hash < ::Hash
       include JRuby::Synchronized
     end
 
-  elsif Concurrent.on_rbx?
+  elsif Concurrent.on_rbx? || Concurrent.on_truffle?
     require 'monitor'
     require 'concurrent/thread_safe/util/array_hash_rbx'