Windows: Timer APIs are not Security APIs

Windows: Timer APIs are not Security APIs

There are currently no callers inside IoTivity that are dependent on
these registerTimer and unregisterTimer exports. Also, callers can
get access to these APIs by linking with static lib c_common.

Given these circumstances, one might argue that octbstack.dll should
not exports these two functions. But, they were already exported in
IoTivity 1.2, so they might be important for compatibity with
hypothetical already-existing IoTivity apps on Windows.

Change-Id: I708d8230e3b6e2f631e89fae2d9b3fab41c93108
Signed-off-by: Dan Mihai <Daniel.Mihai@microsoft.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/19239
Tested-by: jenkins-iotivity <jenkins@iotivity.org>
Reviewed-by: Kevin Kane <kkane@microsoft.com>
Reviewed-by: Dave Thaler <dthaler@microsoft.com>