Merge "Fix LruCache, allow std:string caching" am: 1477714262

Original change: https://android-review.googlesource.com/c/platform/system/core/+/2627034

Change-Id: I633542894afa2dd1a8a6f84c222097bd41a4e68e
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>