Adds the new NNAPI Delegate to libtflite_static so that the NNAPI

Benchmark app can use it.

This app is the sole user of this library.

Bug: 111008127
Bug: 113562636

Test: Covered by existing test:
com.example.android.nn.benchmark.NNTest

Change-Id: I902a91ca87d429d7ebeac88e33cb07095b9b7f0f
Merged-In: I902a91ca87d429d7ebeac88e33cb07095b9b7f0f
(cherry picked from commit e5cb643c)