add missing file FindQuadMath.cmake to CMakeLists.txt

Maybe this MR could also be cherry-picked into the releases/2.7 branch

This problem is in the release, right? In which module is this triggered?

merged

mentioned in commit d98d8e95

mentioned in merge request dune-istl!350 (merged)

Whenever you use installed dune-modules there will be a warning about a missing FindQuadMath module file, so it is never added as feature. This warning even shows up when using dune-common.

Can not cherry-pick for some reasons

@simon.praetorius You are listed as Reporter, not as Developer. I couldn't fix this. If you want you can request to become a developer, then I'll grant these rights. Or wait what the developer meeting will bring...