csdk: Fixed compiler warnings in ocstack.c
csdk: Fixed compiler warnings in ocstack.c

-Wformat= warning fixed by changing the ssanf %lld flag to SCNd64
-Wunused-function fixed by removing the OCSetNetworkMonitorHandler
 function. Since the function is not used it is also not maintained
 it is best to remove the code.

Change-Id: Ib82e6e77a561ac8713cc77bdecc44a5ce42cefff
Signed-off-by: George Nash <acbdc39d528a4315fe0b532d55c50ae46f5c1667@intel.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/17813
Reviewed-by: Mike Fenelon <765c1ea1ad8b7b919b9c046cb20b518277e493ca@microsoft.com>
Tested-by: jenkins-iotivity <d95b56ce41a2e1ac4cecdd398defd7414407cc08@iotivity.org>
Reviewed-by: Dan Mihai <ba8e1833495515b49ded9e20cae80a8129155aa9@microsoft.com>

iotivity/iotivity,iotivity/iotivity,rzr/iotivity,iotivity/iotivity,iotivity/iotivity,rzr/iotivity,iotivity/iotivity,rzr/iotivity,iotivity/iotivity,iotivity/iotivity,rzr/iotivity,rzr/iotivity,rzr/iotivity,iotivity/iotivity,rzr/iotivity