Warning and review notes fixes.

WITH_WINRT -> ENABLE_WINRT_MODE;
Some temporary char* replaced with Ptr<char>;
Build fix for regular WIN32;
Windows Platform SDK and MSVC search added to cmake;
Warinig fixes.

modules/core/test/test_main.cpp

@@ -1,3 +1,7 @@
+#ifdef HAVE_WINRT
+    #pragma warning(disable:4447) // Disable warning 'main' signature found without threading model
+#endif
+
 #include "test_precomp.hpp"
 
 CV_TEST_MAIN("cv")