mruby/mruby — pull request #1217 by skandhas (2013-04-27 08:47:59+00:00)
Title: detect cyclic-include in Module#include

detect cyclic-include in *Module#include*.

Example:

```Ruby
module M end
module N end

module M
include N
end

module N
include M
end
```
CRuby throw a ArgumentError and message: ‘cyclic include detected’ . So mruby should do the same.