Remove old Visual C++ 6 workaround

The changeset 41473987e50d123be1672fb7eaee45bbd60d8fca was never merged to release,
and doesn't appear to be needed since Visual C++6 isn't supported any more. With this change, the only real difference between master and develop is Stephen Kelly's removal of other Visual C++ 6 workarounds (d4a8c7049a66663342c702d88802f518f403b5df).

If you don't want to revert the old change, it could be cherry picked to master instead:

    git cherry-pick 41473987e50d123be1672fb7eaee45bbd60d8fca