* fhandler.h (fhandler_dev_raw): Add definition for method

    * fhandler.h (fhandler_dev_raw): Add definition for method
        `fixup_after_fork'.
        * fhandler_raw.cc (fhandler_dev_raw::fhandler_dev_raw): Add
        `set_need_fixup_after_fork' call.
        (fhandler_dev_raw::~fhandler_dev_raw): Revert to user space
        allocation.
        (fhandler_dev_raw::open): Ditto.
        (fhandler_dev_raw::dup): Ditto. Reset buffer pointer.
        (fhandler_dev_raw::fixup_after_fork): New function.
        * fhandler_tape.cc (fhandler_dev_tape::open): Revert to user space
        memory allocation.
        (fhandler_dev_tape::ioctl): Ditto. Change behaviour on MTSETBLK when
        new size is 1.