logd: statistics per-pid filter

Primarily gives access to the Chattiest TIDs and TAGs
associated with a pid.

Has a secondary effect of allowing us to pull out the
command line, comm and in some cases the associated
PACKAGE for a specific pid while the logs are still
present even if the executable is gone.

Bug: 26029733
Bug: 21615139
Change-Id: I1ea63165a680a9318360579b70b1512078ed5682