CI: Run tests in valgrind
Matthias recently did a bunch of leak fixing in my tests and I was slightly embarrassed about committing such leaky code and not having done that work myself.
That's when I thought about CI and its job being to save me from embarrassment, so can we make it run tests under valgrind or some other form of memory leak detection?
I guess the main problem is that GDK can't really unref() displays, but at least the tests that don't need a display (CSS parser, listmodels, ...) could be made to run that way?