logd: decouple LogTags from LogBuffer

LogBuffer needs a pointer to LogTags, but it should not own the
instance.  It should not provide accessors into LogTags either.

Also, clean up CommandListener a bit.

Test: logging unit tests
Change-Id: Ic0c86a2bac0c4dd80262278588b9fdc2326dbe5b
6 files changed
tree: adb99741f2fbdbc8c8146503939d0fc99839a814
  1. liblog/
  2. logcat/
  3. logd/
  4. logwrapper/