liblog: gate write on log id available

(cherry pick from commit c33103c440517ae8fa5589c22eef795627adf793)

- Secure LOG_ID_KERNEL in writer
- Secure LOG_ID_SECURITY in reader and writer
- if writer transport says not available, do not write to that log id

Bug: 27566046
Bug: 27896341
Change-Id: If63a78a56fb94adfbf9979454c4cadb81af45c19
4 files changed
tree: 59896e9b78537fbee1227d4f8135c334d0ec033e
  1. liblog/
  2. logcat/
  3. logd/
  4. logwrapper/