select tests, pselect tests: Refactor. * tests/test-select.h: New file, extracted from tests/test-select.c. (select_fn): New type. (test, do_select, do_select_nowait, do_select_wait, test_tty, test_connect_first, test_accept_first, test_pair, test_socket_pair, test_pipe): Add my_select argument. (test_function): Renamed from main. Add my_select argument. * tests/test-select.c: Move most code to tests/test-select.h. Include test-select.h. * modules/select-tests (Files): Add tests/test-select.h. * tests/test-pselect.c: Include test-select.h instead of test-select.c. (my_select, main): New functions. * modules/pselect-tests (Files): Add tests/test-select.h, tests/macros.h, tests/signature.h. (Depends-on): Remove select-tests. Add dependencies of test-select.h. (configure.ac): Check for <sys/wait.h>.