Get Include Directory in Dependencies

[cwfitzgerald]

I have a situation where I have another C dependency that requires use of SDL2. I figured that it would be easy enough to just have my mylib-sys crate have a dependency on sdl2-sys with the bundled SDL2. This would bring sdl2 in for linking on all platforms I care about, and solve the problem of building SDL2. However that code needs the SDL2 headers too.

As of right now, as far as I can tell, there is no way to get an include directory for SDL2 from sdl2-sys. It would be really nice to use the kind of information sharing shown in the cargo docs to pass that information from the sdl2-sys build script to be able to use the include directory provided/found by the crate.

I will be working on a patch to try to add this functionality, which I can PR upstream if there is interest.