Transform GNU-makefile tests to CMake
ROOT’s main test suite roottest has several tests that still use GNU-Makefiles.
For Windows, to ease maintenance, and to get rid of a legacy tool called
rmkdepend we need to transform them to CMake.
Start with a simple one, e.g.
Less GNU-Makefiles, more consistent / complete CMake-based setup.
Basic CMake and GNU make knowledge; there is nothing ROOT specific.