Previously, the tests did not run because the CMake version shipped with
Ubuntu 20.04 does not understand the `--test-dir` option and silently
fails.
Change-Id: I335e1d9e3890aa56e66a9dfd0fccd4594a84a08c
* Ubuntu 18.04 GCC does not fully support C++17, hence remove the
runner.
* Using CMake SuiteSparse in a C++17 project requires a workaround
implemented in a recent release.
Change-Id: I9985fe12d582dfc9b74e97d670828334e507e9f5
Sergiu Deitsch