posix: Use poll instead, when available, removing use of select.
* configure.ac (HAVE_POLL_H): Add the check. * src/ath.c [!HAVE_POLL_H] (ath_select): Enable conditionally. * src/posix-io.c [HAVE_POLL_H] (_gpgme_io_select_poll): Use poll. * tests/gpg/t-cancel.c [HAVE_POLL_H] (do_select): Use poll. * tests/gpg/t-eventloop.c [HAVE_POLL_H] (do_select): Use poll.
- GnuPG-bug-id: T2385
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>