bbf00a6231
OSL requires RTTI to be off, this is done with the /GR- flag for MSVC, however /GR is in the default CXX flags leading to warning D9025 : overriding '/GR' with '/GR-' which cannot be suppressed. /GR is on by default and this flag is not required, so removing it from the default CXX flags makes it possible later use /GR- without generating warnings.