The API relied on /proc/timer_stats which has been removed from the
kernel in 2017. Since then, the API has been non-functional (yet
incorrectly reporting support because the support test was buggy).
Just remove it completely. The debian codesearch does not uncover any
API users. Also, I doubt that any new API (based on tracing scheduler
events as perf would do) would map well to what exists now. i.e. if
something like this is re-implemented in UPower or elsewhere, then the
API should likely look different.
And, realistically, if this does need root privileges (i.e. can't be
moved to use BPF programs or so on user units), then we can also create
a new small daemon that is launched on-demand just for that.
The daemon sources and libupower-glib were built without their historic
log domains which meant some debug messages did not appear when running
upowerd in verbose mode.
This fixes the test_no_poll_batteries test.
