lib: do not attempt to close(0) in sysfs_deinit()

If the 'open' fails we 'goto err' which runs 'sysfs_deinit()' on a 'cxt'
which hasn't been fully initialised. The 'dir_fd' is still 0, so
sysfs_deinit calls "close(0)".

Addresses: https://bugzilla.novell.com/show_bug.cgi?id=714151
Reported-by: Diego Ercolani <diego.ercolani@gmail.com>
Analysed-by: Neil Brown <nfbrown@suse.com>
Signed-off-by: Petr Uzel <petr.uzel@suse.cz>

lib/sysfs.c

@@ -140,6 +140,7 @@ int sysfs_init(struct sysfs_cxt *cxt, dev_t devno, struct sysfs_cxt *parent)
 	int fd, rc = 0;
 
 	memset(cxt, 0, sizeof(*cxt));
+	cxt->dir_fd = -1;
 
 	if (!sysfs_devno_path(devno, path, sizeof(path)))
 		goto err;