Features:
+* when killing due to service watchdog timeout maybe detect whether target
+ process is under ptracing and then log loudly and continue instead.
+
* tweak journald context caching. In addition to caching per-process attributes
keyed by PID, cache per-cgroup attributes (i.e. the various xattrs we read)
keyed by cgroup path, and guarded by ctime changes. This should provide us