IOT-1835 Make resource/csdk/security W4 compliant.

IOT-1835 Make resource/csdk/security W4 compliant.

These changes include the following:
- Prepare resource/csdk/security/SConscript to enable /W4.
- Fix W4 warnings under resource/csdk/security/src
- Fix W4 warnings under resource/csdk/security/tool

Changes to resource/csdk/security/provisioning will come in another review.

Change-Id: I3a26fa952103b3b218569155cd1341aa696944e1
Signed-off-by: Alex Kelley <alexke@microsoft.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/17399
Reviewed-by: Kevin Kane <kkane@microsoft.com>
Tested-by: jenkins-iotivity <jenkins@iotivity.org>