This is a port of 70002c80 to z/OS to fix the same potential issue that
could effectively enter an infinite loop (but not a busy loop) under
certain conditions when polling for events.
PR-URL: https://github.com/libuv/libuv/pull/2725
Reviewed-By: Fedor Indutny <fedor.indutny@gmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
Reviewed-By: Jameson Nash <vtjnash@gmail.com>