Always include raw OS version number on Windows

src/FeatureConfig.cc

@@ -333,6 +333,7 @@ std::string getOperatingSystemInfo()
 #ifdef _WIN64
   rv << " (x86_64)";
 #endif // _WIN64
+  rv << " (" << ovi.dwMajorVersion << "." << ovi.dwMinorVersion << ")";
   return rv.str();
 #else //! _WIN32
 #ifdef HAVE_SYS_UTSNAME_H