LU-5417 lustre: fix comparison between signed and unsigned

LU-5417 lustre: fix comparison between signed and unsigned

Cleanup in general headers.
* use size_t in cfs_size_round*()
* make unsigned index and len in lustre_cfg_*() and object_update_*()
* make iteration variable the same type as comparing value
* make unsigned pages counters
* fix printf formats

Signed-off-by: Dmitry Eremin <dmitry.eremin@intel.com>
Change-Id: I9af487f0c8e04825adfce94ae11fe0a64c71c2e5
Reviewed-on: http://review.whamcloud.com/11327
Tested-by: Jenkins
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Fan Yong <fan.yong@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>