tar: fix crash on broken tar file.
gsf_infile_tar_read (GsfInput *input, size_t num_bytes, guint8 *buffer)
{
	(void)input;
	(void)num_bytes;
	(void)buffer;
	return NULL;
}

gsf_infile_tar_read (GsfInput *input, size_t num_bytes, guint8 *buffer)
{
	(void)input;
	(void)num_bytes;
	(void)buffer;
	return NULL;
}
