Xdmf fixes
This PR fixes the build of Xdmf3 for system libxml2/HDF5. Additonally, it clarifies the logic for libxml2 finding.
(Originally submitted as a PR on github by @nschloe: https://github.com/Kitware/VTK/pull/21)
This PR fixes the build of Xdmf3 for system libxml2/HDF5. Additonally, it clarifies the logic for libxml2 finding.
(Originally submitted as a PR on github by @nschloe: https://github.com/Kitware/VTK/pull/21)