Merge changes I5149433c,Iff6f248d,Ib6432177 into oc-mr1-dev

* changes:
  Allow implicit padding
  Allow Conv2D and FullyConnected use multiple thread.
  Allow ADD and MUL taking quantized input.
tree: 83158a744d48d7b45f016311d780262d24443b78
  1. nn/
  2. Android.bp