DO NOT MERGE: common_time: Turn the logging up to 11

Actually, despite the CL title, no addition log messages are being
sent to logcat.  Generally speaking, the common_time service tends to
be rather quiet from a log perspective.  Events related to master
election and arbitration as well as state changes tend to be
infrequent in steady state operation.  Unfortunately, if there is a
problem with the system, it frequently gets pushed out of logcat by
other messages and is missing from the logs when a bugreport is
finally taken.

This change adds a utility class which can be used to store the last N
log message in a ring buffer to be dumped later during a dumpsys
operation.  Three internal log buffers were added to the system.  One
to record messages having to do with state transitions.  Another was
added to record traffic relating to master election, and one final
buffer to record basic data on packets which were received but
discarded for any reason.  During a bugreport, these common_time.clock
service will be able to dump these messages regardless of the amt of
other logcat activity, which should assist in debugging long running
issues.

Change-Id: Ic3bbf7480c8978f9bf82bafaba04cf4586db60cf
Signed-off-by: John Grossman <johngro@google.com>