This function sets a stream to nonblocking mode. When data arrives on
the stream, read_callback will be called with some or all of this
data. When the stream has buffer space over for writing,
write_callback will be called so that you can write more data to it.
If the stream is closed at the other end, close_callback will be
called.
When out-of-band data arrives on the stream, read_oob_callback will
be called with some or all of this data. When the stream allows
out-of-band data to be sent, write_oob_callback will be called so that
you can write out-of-band data to it.
All callbacks will have the id of file as first argument when called
(see Stdio.File.set_id).
If no arguments are given, the callbacks will not be changed. The
stream will just be set to nonblocking mode.