SDL_CreateDirectories / SDL_CreatePath

[luppichristian]

On Win32 SDL_CreateDirectory only works if the last specified folder name in path has to be created. It would be useful to implement a function called for example SDL_CreateDirectories or SDL_CreatePath that actually creates all the missing folders. Maybe this behaviour could be implemented in SDL_CreateDirectory directly.

[icculus]

There was some reason we didn't do this, but I can't remember why; I'm going to poke around the issue tracker and try to figure that out later today. If I can't find a good reason, we'll add this.