* select.cc (peek_pipe): Reorganize slightly. Don't attempt to check a handle
if it has ongoing I/O.
(select_pipe_info::select_pipe_info): Delete definition.
(select_pipe_info::~select_pipe_info): Delete definition.
(thread_pipe): Get rid of WFMO call. Reorganize loop.
(pipe_cleanup): Remove dependence on destructor.
(thread_serial): Reorganize loop.
* select.h (select_pipe_info): Empty this class since it no longer has any
special requirements (for now).
* syscalls.cc (readv): Remove an unneeded debug printf.