* fhandler.h (fhandler_base::ready_for_read): Remove unused argument.

* fhandler.h (fhandler_base::ready_for_read): Remove unused argument.
(fhandler_tty_slave::ready_for_read): Ditto.
(select_record): Remove poll, initialize peek.
* select.cc: Remove all poll functions, throughout.  Change second argument of
peek_* functions to 'bool' throughout.  Specifically initialize *_ready
variables throughout.
(select_stuff::poll): Subsume previous poll functionality.
(peek_pipe): Don't grab guard mutex when in select loop.  select()/read() is
racy by design so there is no need to worry about a race in select().
(fhandler_base::ready_for_read): Remove unused argument.
(fhandler_tty_slave::ready_for_read): Ditto.
* syscalls.cc (_read): Eliminate third argument in ready_for_read call.