IOT-1583: Removing /W4 warning from resource/c_common.

IOT-1583: Removing /W4 warning from resource/c_common.

First batch of refactoring changes to remove /W4 compiler warnings.
For now I'm starting with resource/c_common and adding
_CRT_SECURE_NO_WARNINGS to disable warnings about issues we cannot
change anyway, because the code has to build for multiple platforms.

Change-Id: I03d088f8a7c3263ea994fe075fbb579a14e31f0c
Signed-off-by: Pawel Winogrodzki <pawelwi@microsoft.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/15725
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Dan Mihai <Daniel.Mihai@microsoft.com>