clutter test: add Clutter::ShaderEffect tests

* clutter depends cogl.
* Cogl::Handler(CoglHandler) and Cogl::INVALID_HANDLE(COGL_INVALID_HANDLE)
  appears in C library code.
  But, Ruby-GNOME2 does not have (gi based) cogl binding.

  Should it do treat cogl?

  - make gi based cogl binding to easliy treat cogl related things.
    e.g. Cogl::INVALID_HANDLE constant
  - use magic number to treat code which is related to cogl.(sees to be
	bad.... Now using this workaround, sorry.)