/*
 * call-seq:
 *
 *      Kgio.accept_nonblock = true
 *      Kgio.accept_nonblock = false
 *
 * Sets whether or not Kgio::Socket objects created by
 * TCPServer#kgio_accept,
 * TCPServer#kgio_tryaccept,
 * UNIXServer#kgio_accept,
 * and UNIXServer#kgio_tryaccept
 * are created with the O_NONBLOCK file status flag.
 *
 * This defaults to +false+ for GNU/Linux where MSG_DONTWAIT is
 * available (and on newer GNU/Linux, accept4() may also set
 * the non-blocking flag.  This defaults to +true+ on non-GNU/Linux
 * systems.
 */
static VALUE set_nonblock(VALUE mod, VALUE boolean)
{
        switch (TYPE(boolean)) {
        case T_TRUE:
                accept4_flags |= SOCK_NONBLOCK;
                return boolean;
        case T_FALSE:
                accept4_flags &= ~SOCK_NONBLOCK;
                return boolean;
        }
        rb_raise(rb_eTypeError, "not true or false");
        return Qnil;
}