logd: rename mOldest -> oldest_

I added mOldest recently before mentally committing to have new code
follow the Google C++ style guide.

Test: build
Change-Id: I6d5bab5833e14ac3808862598a2a60989d805e18
2 files changed
tree: 8fae5be0e50fe155018f042281b517c679e96740
  1. liblog/
  2. logcat/
  3. logd/
  4. logwrapper/