* select.cc (set_handle_or_return_if_not_open): Remove unneeded final backslash
from definition.
(cygwin_select): Reorganize to incorporate outer retry loop. Move remaining
time recalculation here for retry case. Use select_stuff::wait_states for loop
control.
(select_stuff::cleanup): Avoid unneeded initialization.
(select_stuff::wait): Modify definition to return select_stuff::wait_states.
Eliminate is_cancelable. Don't element 1 of an array if it is a cancel handle.
Remove loop. Rely on being called from enclosing loop in cygwin_select.
Remove time recalculation when restarting. Try harder to always return from
the bottom.
* select.h (select_stuff::wait_state): New enum.
(select_stuff::wait): Modify declaration to return select_stuff::wait_states.