ocamlsdl 0.9.1 (new formula)

Added SDL OCaml binding [ocamlsdl](http://ocamlsdl.sourceforge.net/).
There is no particular issue to know about it.
Can this test be modified to do something more substantial then e.g. `--version` or `--help`? See `cmake.rb` for an example of a formula with a good test. Thanks!