[JFFS2] Fix potential memory leak of dead xattrs on unmount.

An xattr_datum which ends up orphaned should be freed by the GC
thread. But if we umount before the GC thread is finished, or if we
mount read-only and the GC thread never runs, they might never be
freed. Clean them up during unmount, if there are any left.

Signed-off-by: David Woodhouse <[e-mail]>

fs/jffs2/xattr.c

···
 		list_del(&xd->xindex);
 		jffs2_free_xattr_datum(xd);
 	}
+	list_for_each_entry_safe(xd, _xd, &c->xattr_unchecked, xindex) {
+		list_del(&xd->xindex);
+		jffs2_free_xattr_datum(xd);
+	}
 }
 
 #define XREF_TMPHASH_SIZE	(128)