Releases the resources (e.g., memory) used by file.

If file is for a file-system file (i.e., it was created by NewFileStream_ns), that file will be closed, if necessary, but will not be deleted.

If instead this stream is for a memory buffer (created by NewMemoryStream_ns), this function will not free any memory buffer passed to it by SetStreamContents_ns.

It is okay if file is NULL (no action is taken).