liblog: remove unused parts of android_log_transport_context
am: e99d6cedbf

Change-Id: I72351d78c105c2662fc0d0def6985ee43787bb86
tree: ccfc0c0ed15ab710875fb9a4e0aecba1f0db6d71
  1. liblog/
  2. logcat/
  3. logd/
  4. logwrapper/