Fix all Sphinx reference warnings in `Doc/library/select.rst`

Doc/library/select.rst:243: py:const reference target not found: POLLIN [ref.const]
Doc/library/select.rst:243: py:const reference target not found: POLLPRI [ref.const]
Doc/library/select.rst:243: py:const reference target not found: POLLOUT [ref.const]
Doc/library/select.rst:275: py:const reference target not found: POLLIN [ref.const]
Doc/library/select.rst:275: py:const reference target not found: POLLOUT [ref.const]
Doc/library/select.rst:309: py:const reference target not found: EPOLLIN [ref.const]
Doc/library/select.rst:311: py:const reference target not found: EPOLLOUT [ref.const]
Doc/library/select.rst:313: py:const reference target not found: EPOLLPRI [ref.const]
Doc/library/select.rst:315: py:const reference target not found: EPOLLERR [ref.const]
Doc/library/select.rst:317: py:const reference target not found: EPOLLHUP [ref.const]
Doc/library/select.rst:319: py:const reference target not found: EPOLLET [ref.const]
Doc/library/select.rst:322: py:const reference target not found: EPOLLONESHOT [ref.const]
Doc/library/select.rst:325: py:const reference target not found: EPOLLEXCLUSIVE [ref.const]
Doc/library/select.rst:330: py:const reference target not found: EPOLLRDHUP [ref.const]
Doc/library/select.rst:333: py:const reference target not found: EPOLLRDNORM [ref.const]
Doc/library/select.rst:333: py:const reference target not found: EPOLLIN [ref.const]
Doc/library/select.rst:335: py:const reference target not found: EPOLLRDBAND [ref.const]
Doc/library/select.rst:337: py:const reference target not found: EPOLLWRNORM [ref.const]
Doc/library/select.rst:337: py:const reference target not found: EPOLLOUT [ref.const]
Doc/library/select.rst:339: py:const reference target not found: EPOLLWRBAND [ref.const]
Doc/library/select.rst:341: py:const reference target not found: EPOLLMSG [ref.const]
Doc/library/select.rst:343: py:const reference target not found: EPOLLWAKEUP [ref.const]
Doc/library/select.rst:346: py:const reference target not found: EPOLLEXCLUSIVE [ref.const]
Doc/library/select.rst:350: py:const reference target not found: EPOLLWAKEUP [ref.const]
Doc/library/select.rst:429: py:const reference target not found: POLLIN [ref.const]
Doc/library/select.rst:429: py:const reference target not found: POLLPRI [ref.const]
Doc/library/select.rst:429: py:const reference target not found: POLLOUT [ref.const]
Doc/library/select.rst:438: py:const reference target not found: POLLIN [ref.const]
Doc/library/select.rst:440: py:const reference target not found: POLLPRI [ref.const]
Doc/library/select.rst:442: py:const reference target not found: POLLOUT [ref.const]
Doc/library/select.rst:444: py:const reference target not found: POLLERR [ref.const]
Doc/library/select.rst:446: py:const reference target not found: POLLHUP [ref.const]
Doc/library/select.rst:448: py:const reference target not found: POLLRDHUP [ref.const]
Doc/library/select.rst:451: py:const reference target not found: POLLNVAL [ref.const]
Doc/library/select.rst:459: py:const reference target not found: ENOENT [ref.const]
Doc/library/select.rst:477: py:const reference target not found: POLLIN [ref.const]
Doc/library/select.rst:477: py:const reference target not found: POLLOUT [ref.const]
Doc/library/select.rst:525: py:class reference target not found: eventlist [ref.class]
Doc/library/select.rst:566: py:const reference target not found: KQ_FILTER_READ [ref.const]
Doc/library/select.rst:569: py:const reference target not found: KQ_FILTER_WRITE [ref.const]
Doc/library/select.rst:572: py:const reference target not found: KQ_FILTER_AIO [ref.const]
Doc/library/select.rst:574: py:const reference target not found: KQ_FILTER_VNODE [ref.const]
Doc/library/select.rst:577: py:const reference target not found: KQ_FILTER_PROC [ref.const]
Doc/library/select.rst:579: py:const reference target not found: KQ_FILTER_NETDEV [ref.const]
Doc/library/select.rst:582: py:const reference target not found: KQ_FILTER_SIGNAL [ref.const]
Doc/library/select.rst:585: py:const reference target not found: KQ_FILTER_TIMER [ref.const]
Doc/library/select.rst:595: py:const reference target not found: KQ_EV_ADD [ref.const]
Doc/library/select.rst:597: py:const reference target not found: KQ_EV_DELETE [ref.const]
Doc/library/select.rst:599: py:const reference target not found: KQ_EV_ENABLE [ref.const]
Doc/library/select.rst:601: py:const reference target not found: KQ_EV_DISABLE [ref.const]
Doc/library/select.rst:603: py:const reference target not found: KQ_EV_ONESHOT [ref.const]
Doc/library/select.rst:605: py:const reference target not found: KQ_EV_CLEAR [ref.const]
Doc/library/select.rst:607: py:const reference target not found: KQ_EV_SYSFLAGS [ref.const]
Doc/library/select.rst:609: py:const reference target not found: KQ_EV_FLAG1 [ref.const]
Doc/library/select.rst:611: py:const reference target not found: KQ_EV_EOF [ref.const]
Doc/library/select.rst:613: py:const reference target not found: KQ_EV_ERROR [ref.const]
Doc/library/select.rst:620: py:const reference target not found: KQ_FILTER_READ [ref.const]
Doc/library/select.rst:620: py:const reference target not found: KQ_FILTER_WRITE [ref.const]
Doc/library/select.rst:626: py:const reference target not found: KQ_NOTE_LOWAT [ref.const]
Doc/library/select.rst:628: py:const reference target not found: KQ_FILTER_VNODE [ref.const]
Doc/library/select.rst:634: py:const reference target not found: KQ_NOTE_DELETE [ref.const]
Doc/library/select.rst:636: py:const reference target not found: KQ_NOTE_WRITE [ref.const]
Doc/library/select.rst:638: py:const reference target not found: KQ_NOTE_EXTEND [ref.const]
Doc/library/select.rst:640: py:const reference target not found: KQ_NOTE_ATTRIB [ref.const]
Doc/library/select.rst:642: py:const reference target not found: KQ_NOTE_LINK [ref.const]
Doc/library/select.rst:644: py:const reference target not found: KQ_NOTE_RENAME [ref.const]
Doc/library/select.rst:646: py:const reference target not found: KQ_NOTE_REVOKE [ref.const]
Doc/library/select.rst:648: py:const reference target not found: KQ_FILTER_PROC [ref.const]
Doc/library/select.rst:654: py:const reference target not found: KQ_NOTE_EXIT [ref.const]
Doc/library/select.rst:656: py:const reference target not found: KQ_NOTE_FORK [ref.const]
Doc/library/select.rst:658: py:const reference target not found: KQ_NOTE_EXEC [ref.const]
Doc/library/select.rst:660: py:const reference target not found: KQ_NOTE_PCTRLMASK [ref.const]
Doc/library/select.rst:662: py:const reference target not found: KQ_NOTE_PDATAMASK [ref.const]
Doc/library/select.rst:664: py:const reference target not found: KQ_NOTE_TRACK [ref.const]
Doc/library/select.rst:666: py:const reference target not found: KQ_NOTE_CHILD [ref.const]
Doc/library/select.rst:669: py:const reference target not found: KQ_NOTE_TRACKERR [ref.const]
Doc/library/select.rst:671: py:const reference target not found: KQ_FILTER_NETDEV [ref.const]
Doc/library/select.rst:677: py:const reference target not found: KQ_NOTE_LINKUP [ref.const]
Doc/library/select.rst:679: py:const reference target not found: KQ_NOTE_LINKDOWN [ref.const]
Doc/library/select.rst:681: py:const reference target not found: KQ_NOTE_LINKINV [ref.const]