(lsh_oop_stop_callback): New function.
(lsh_oop_stop): New function.
(lsh_oop_cancel_stop): New function.
(io_nfiles): New function.
(close_fd): Decrement nfiles, and call lsh_oop_stop when no files
are left.
(make_lsh_fd): Increment nfiles.

Rev: src/io.c:1.160
Rev: src/io.h:1.88