[!261] [cmake] Guard the grid analysis tool correctly

Merge branch 'feature/guard-grid-analysis' into 'master'

consistent-grid-orientation is merely a suggestion. dune-perftool should
perfectly build in its absence.

See merge request [dominic/dune-perftool!261]

  [dominic/dune-perftool!261]: gitlab.dune-project.org/dominic/dune-perftool/merge_requests/261