On some systems, the type of the length of a slice is different from the nfds_t type, so cast the slice length to nfds_t. This is already done in poll, so just copy that implementation for ppoll.
On some systems, the type of the length of a slice is different from the nfds_t type, so cast the slice length to nfds_t. This is already done in poll, so just copy that implementation for ppoll.