BUG: Do not import module site when initializing python interpreter

This MR fix CMB test failures that caused by initializing python
environment incorrectly. If needed, user can import site module later
after initialization.

smtk/common/PythonInterpreter.cxx

@@ -36,6 +36,10 @@ using boost::regex_search;
 using boost::regex_match;
 #endif
 SMTK_THIRDPARTY_POST_INCLUDE
+#if WIN32
+#include <Python.h>
+extern __declspec(dllimport) int Py_NoSiteFlag;
+#endif
 
 namespace
 {
@@ -72,6 +76,7 @@ void PythonInterpreter::initialize()
 {
   if (!this->isInitialized())
   {
+    Py_NoSiteFlag = 1;
     pybind11::initialize_interpreter();
 
     // Add the contents of our python path list to the path