math/vtk9: Add workaround for a regression in VTK that requires qmake and moc

find_package(VTK QUIET COMPONENTS GUISupportQt) erroneously
requires qmake and moc to be present.

misc/visp regressed for this reason after VTK was updated to 9.2.2
even though VTK is only a proxy dependency for visp.

Reported by: fallout