mruby/mruby — pull request #1708 by Fleurer (2014-02-14 05:27:53+00:00)
Title: cleanup warnings in hash.c

```
/home/fleuria/code/mruby/src/hash.c:159:1: warning: ‘mrb_hash_dp`defined but not used [-Wunused-function]
mrb_hash_dup(mrb_state *mrb, mrb_value hash)
^
```

this commit defines Hash#dup to use `mrb_hash_dup` in hash.c, however it seems that Hash#dup is not in the ISO standard yet.