CppTools: Add dummy macro for __thiscall

Change-Id: If2ccfe9ff40539404ed0f40c06c71a73ee661e2d
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>

src/plugins/cpptools/cppmodelmanager.cpp

@@ -129,6 +129,7 @@ static const char pp_configuration[] =
     // ### add macros for win32
     "#define __cdecl\n"
     "#define __stdcall\n"
+    "#define __thiscall\n"
     "#define QT_WA(x) x\n"
     "#define CALLBACK\n"
     "#define STDMETHODCALLTYPE\n"