GLib.FileUtils.close closes a file descriptor, so that it no longer refers to any file and may be reused.
Any record locks held on the file it was associated with, and owned by the process, are removed (regardless of the file descriptor that was used to obtain the lock).
If fd is the last copy of a particular file descriptor the resources associated with it are freed; if the descriptor was the last reference to a file which has been removed using GLib.FileUtils.unlink the file is deleted.
returns zero on success. On error, -1 is returned, and GLib.errno is set appropriately.