[cmake] Guard the grid analysis tool correctly

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

bin/analyzegrid/CMakeLists.txt

-add_executable(analyze_grid analyze_grid.cc)
-dune_symlink_to_source_files(FILES test_2d_structured.ini test_3d_structured.ini test_2d_unstructured.ini test_3d_unstructured.ini)
+if(consistent-edge-orientation_FOUND)
+  add_executable(analyze_grid analyze_grid.cc)
+  dune_symlink_to_source_files(FILES test_2d_structured.ini test_3d_structured.ini test_2d_unstructured.ini test_3d_unstructured.ini)
+endif()