This function was defined in the Header file, but
had been moved from the .cpp file. I'm assuming it
was removed since there aren't any special memory
handling requirements associated with a folder_context.
I could have removed the def from the header file,
but I felt it better to keep an extremely consistent
interface. Today, we don't have any special needs
with the folder_context, but in the future we could
want to do some other cleanup/etc. So, to fix this
issue, I created a simple drop-in sass_free_folder_context
method.

This issue was blocking Ruby from building the library.
Using consistent spacing to the rest of the file for a single-line function.