AddQuadMathFlags
----------------

Helpers for using `QuadMath <https://gcc.gnu.org/onlinedocs/libquadmath>`_
from DUNE targets.

.. cmake:command:: add_dune_quadmath_flags

  Link the given targets against ``QuadMath::QuadMath`` and add the compile
  definition ``HAVE_QUADMATH=1``.

  The command has an effect only when ``QuadMath_FOUND`` is true.

  .. code-block:: cmake

    add_dune_quadmath_flags(<target> [<target>...])

  ``targets``
    One or more existing targets to configure.