logging: add format checks for printf input

logging: add format checks for printf input

This patch makes gcc aware that this is a function formating a string,
this way gcc is able to check if the format string is correct and warn
the user otherwise. This should make it possible to find some more
problems in the code.

Change-Id: I27058eb1d5c3352e6f872e4013eedb94d42d757a
Signed-off-by: Hauke Mehrtens <hauke.mehrtens@lantiq.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/2935
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Patrick Lankswert <patrick.lankswert@intel.com>