Enable buildtin_vdt fixing #261

[DraTeots]

Checklist

• Used a personal fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged) - NO as from {% set build_number = os.environ["ROOT_CONDA_BUILD_NUMBER"] %} I thought it is done automatically
• Reset the build number to 0 (if the version changed) - NO (see above)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering) - NO from the documentation it seems not needed
• Ensured the license file is being packaged. - NO license file packaging is not affected

closing #261

[conda-forge-webservices]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe/meta.yaml) and found it was in an excellent condition.

[DraTeots]

It looks like OSX is failing independently of this PR.

[henryiii]

Ah, missed the build number, added the bump manually. The build number from envvar is only for ROOT test builts, the feedstock otherwise sets is normally. Notice the if statement.