Asynchronus partitioned execution, plus minor code cleanup.

Partioned execution is now asynchronous end-to-end, although
the individual execution steps are serialized with respect to
one another.

Other changes:
- Minor code cleanup per comments from previous CL
    https://googleplex-android-review.git.corp.google.com/#/c/platform/frameworks/ml/+/3000624/
  including comments on memory management for
  inter-partition temporaries.
- Remove "simulation" form of partitioning, and renumber
  values of debug.nn.partition property accordingly.
- Fix android:nn:wrapper::Event -- add missing contructor
  and fix comment.

Bug: 63905942
Test: mma (user)
      mma (userdebug)
      ml/nn/runtime/tests (userdebug)
      (and spot check that debug.nn.partition unspecified,
       0, and 1 exhibits the correct control over
       partitioning behavior)

Change-Id: I5767d2144c4a42258444a6445866529919d4fe8d
6 files changed
tree: 57127ed3bdbf50cd2dbf74d5ac3177d40f8e84d4
  1. common/
  2. driver/
  3. runtime/
  4. tools/
  5. Android.bp
  6. README.txt