The build failed, apparently only for Windows but really for all platforms. I think the reason is that an external OpenVDB is not available here.
My opinion is that this could be accepted, but I would suggest to reverse the logic, so that if we do nothing, i.e. no additional symbol is defined, the build is done with the bundled OpenVDB. If someone has a separate OpenVDB, they can define the symbol to have it used.
Of course we can only support the bundled version if something does not work as expected.