If time is counted in jiffies, machine reboot brokes `dirty for`
statistic for caches loaded at boot. The counter overflows and
`dirty for` shows some huge values.
Cast ticks to unsigned long.
Add necessary header.
Move `env_msleep` to `TIME` subgroup of header.
Move `env_time_after` below time converting functions.
Signed-off-by: Slawomir Jankowski <slawomir.jankowski@intel.com>
eef4e49904