The idea of the new stats machinery is that 'stats' becomes an option
that enables the basic stats gathering infrastructure in EMPER. At
some point, it should become a non-user option, i.e., it should be
remove from meson_options.txt. Then comes a layer of fine-grained
stats control switches, which default to 'auto'. Third, a new option
called 'stats_all' is added, which, if enabled, activates all
fine-graind stats knobs that are set to 'auto'.