obdfs/flushd.c: pupdated stopped on module unload.

obdfs/flushd.c: pupdated stopped on module unload.
    check_time now indicates minimum age of buffer to flush, so we can call
    obdfs_enqueue_pages() multiple times with decreasing ages in tight
    memory situations to flush some pages, but not all
obdfs/super.c: fix small memory leaks
obdfs/*.c: partial update to 2.3.42 code (not including 32-bit UID/GID)