[$] Repealing the poll() tax

One of the new features merged for the 4.18 kernel is a new polling interface using the asynchronousI/O mechanism. As part of this work, the internal implementation of howthe various polling-related system calls (poll(),select(), and epoll_wait()) work was significantlychanged. The reporting of a significant performance regression has now putall of that work into doubt, though. While it could be reverted, the morelikely outcome would appear to be another set of changes to how pollingworks in the kernel.