Android p preview 4
Merge changes from topic "nnapi-cherrypick-from-master-and-pi-dev-to-aosp"

* changes:
  NNAPI systrace for timing statistics
  Fix common/operations tests and make easier to run
  Split unknown dimensions test into 16 shards
  Tests for 1.0 device on paths in VersionedIDevice
  Iterate unknown dimensions combinations in code
  Multithreaded test with shared compilation
  Add ubsan build
  Make fully_connected op use reference implementation in certain cases.
  Script for repeatable runs of benchmark
tree: 82aea09fd528c1bd1147e7781e6ad90c2a82ce58
  1. nn/
  2. CleanSpec.mk
  3. OWNERS