* gnu/packages/patches/vtk-8-fix-freetypetools-build-failure.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/image-processing.scm (vtk-8): Dis-inherit from VTK. Use the
package definition that predated the update to VTK 9, taken from commit
f4dc8ac6dfa036d98aa0990ae22268a9650899d0.