Fix build process to not use rustpkg

[darnuria]

like @cptroot say :
The rust master branch is deprecating rustpkg soon, and the build is currently broken even using rustpkg. Is it possible to use a build practice that doesn't depend on rustpkg?

rust-lang/rust#11859
Rust-SDL2/rust-sdl2#41

[jeremyletang]

Hi!

I think about this from a while and i probably will use cmake.
It can allow us to check if all the dependency to build rust-sfml are present (CSFML +SFML +SFML dependency).

Do you think about an other build system?

[darnuria]

Currently I don't know. There is a lot of discussion on rust ML about rustpkg.

@jeremyletang :

Do you think about an other build system?

In my humble opinion, Make, Cmake or other compiling systems are awful...
So I am not a good source of information. :)

[jeremyletang]

I see the discussion in the mailing list, it's really active!

For the moment i use make to build rust-sfml. It's easy to use / common to lot of people, and i don't think we need a complicated build system, since rustpkg should be replaced in a short / moyen term.

[darnuria]

Yeap a good old make is ok. :)

You can close the bug if you want. :D