There's still plenty of work that can be done here, particularly
re-doing the locking so each LogReaderThread does not mutually exclude
the others, but that's out of the scope here.
This change primarily removes the public 'mTimes' from LogBuffer and
creates a new LogReaderList class instead. It would have merged this
into LogReader, but that creates a circular dependency.
This change also removes the need to reference LogReader or
LogReaderList from LogAudit, LogKLog, and LogListener, instead relying
on LogBuffer()::log() to call LogReaderList::NotifyNewLog().
Test: logging unit tests
Change-Id: Ia874b57a9ec1254af1295bfa6f7af2f92a75755b
