EiffelStudio Homebrew package.

I've been told to do a PR here although I'm not sure how this would work for end users to get eiffelstudio without fidling with the homebrew configuration.

Thanks,
Manu
Try this:

```ruby
if Hardware::CPU.ppc?
  platform = "macosx-ppc"
elsif MacOS.prefer_64_bit?
  platform = "macosx-x86-64"
else
  platform = "macosx-x86"
end

system "./compile_exes", platform
```