Azure: CMake does not find MSBuild options

Running cmake in Azure DevOps Pipelines currently fails, e.g. https://dev.azure.com/conda-forge/feedstock-builds/_build/results?buildId=10607&view=logs&jobId=2cc45e14-23e3-52d7-b33a-8c2744410b97&taskId=22e1f59c-6ad0-5e39-c80e-f2cebe3974dd&lineStart=724&lineEnd=725&colStart=1&colEnd=1

The relevant error message is:

```
D:\bld\thrift-cpp_1549275362470\work\build\CMakeFiles\3.13.2\VCTargetsPath.vcxproj(15,2): error MSB4019: The imported project "D:\Microsoft.Cpp.Default.props" was not found. Confirm that the path in the declaration is correct, and that the file exists on disk.
```

This is probably due to a missing `VCTargetsPath`.