`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.