[IOT-1209] Fix provisioningclient for Windows

[IOT-1209] Fix provisioningclient for Windows

1. Include security provisioning code and data just in octbstack.dll,
   instead of duplicating it in provisioningclient.exe.

2. Use octbstack.def instead of dllexport/dllimport, because dllexport
   and dllimport are too fragile.

Change-Id: Ic96e249e71563824ae943883168cae2e56e10937
Signed-off-by: Dan Mihai <Daniel.Mihai@microsoft.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/9993
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Soemin Tjong <stjong@microsoft.com>
Reviewed-by: David Antler <david.a.antler@intel.com>
Reviewed-by: Dave Thaler <dthaler@microsoft.com>