CMake: call CMake's FindHDF5 instead of trying to find everything by hand

[tamiko]

Closes #8957

[tamiko]

/rebuild

[tamiko]

@tjhei With this change HDF5 is now configured and enabled on the CI:

-- Include /jenkins/workspace/dealii_PR-13319/cmake/configure/configure_hdf5.cmake
-- Found HDF5: /usr/lib/x86_64-linux-gnu/hdf5/serial/lib/libhdf5.so;/usr/lib/x86_64-linux-gnu/libpthread.so;/usr/lib/x86_64-linux-gnu/libsz.so;/usr/lib/x86_64-linux-gnu/libz.so;/usr/lib/x86_64-linux-gnu/libdl.so;/usr/lib/x86_64-linux-gnu/libm.so (found version "1.8.16") 
--   HDF5_VERSION: 1.8.16
--   HDF5_LIBRARIES: /usr/lib/x86_64-linux-gnu/hdf5/serial/lib/libhdf5.so;/usr/lib/x86_64-linux-gnu/libpthread.so;/usr/lib/x86_64-linux-gnu/libsz.so;/usr/lib/x86_64-linux-gnu/libz.so;/usr/lib/x86_64-linux-gnu/libdl.so;/usr/lib/x86_64-linux-gnu/libm.so
--   HDF5_INCLUDE_DIRS: /usr/include/hdf5/serial
--   HDF5_USER_INCLUDE_DIRS: /usr/include/hdf5/serial
-- Found HDF5
-- DEAL_II_WITH_HDF5 successfully set up with external dependencies.

... and two HDF5 tests fail for the serial configuration.

I checked, we have not tested a serial configuration with non-mpi hdf5 in about forever. Also, almost all of our hdf5 tests require MPI to be enabled.

So what do?

[tjhei]

Not sure if anyone uses hdf5 without MPI?

I would suggest to require MPI. This makes testing easier for us.

[drwells]

I think that, for the sake of our sanity, we should require MPI with HDF5 for the same reasons we require Trilinos with HDF5.

[tamiko]

@tjhei @drwells Alright. I have made MPI an unconditional dependency for HDF5.

[masterleinad]

Looks good to me.

[bangerth]

The possibilities for extensions of step-3 have a long section on using HDF5 and explicitly state that "Although the HDF5 deal.II binding supports both serial and MPI...". I'm not sure that we ever use HDF5 without MPI, but you might want to read through https://dealii.org/developer/doxygen/deal.II/step_3.html#UsingHDF5tooutputthesolutionandadditionaldata to see what we ought to do.

[tjhei]

to see what we ought to do.

I would be in favor of merging as is and then tackling this separately by somebody who is interested in sequential hdf5:

• Go through all the tests and require MPI where necessary.
• Add several sequential tests.
• Update the cmake detection to allow serial configuration again.