Now 'make check' will additionally build and run the test suites in the
./tests directory. Add initial always successful dummy test suite.
This is done using Automake support for testing.
Automake Manual, 15 Support for test suites
https://www.gnu.org/software/automake/manual/automake.html#Tests
./tests/Makefile.am takes some influence from the same file in the
minimal-gtest-autotools template project.
654848ec01/tests/Makefile.am
Bug 781978 - Add Google Test C++ test framework
Mike Fleetwood