time wrap caused kevent infinite loop

[Slawa Olhovchenkov]

now_ms posible wrap (by design).
As result delta_ms calcultaed as `TICKS_TO_MS(tick_remain(now_ms,
exp)) + 1` can be negative. This caused negative
timeout.tv_sec/timeout.tv_nsec, failed kevent() (EINVAL) and infinite
loop.