[9.18] Remove obsolete epoll/kqueue/devpoll configure options
Since we don't use networking directly but rather via libuv, these configure options were no-op. Remove the configure checks for epoll (Linux), kqueue (BSDs) and /dev/poll (Solaris).
(cherry picked from commit 051f3d61)
Closes #4098 (closed)
Backported from !7973 (merged)
Edited by Ondřej Surý