I added a Mock OEMCrypto implementation with stubs only.
I corrected the "extern C" location in OEMCrypto.h. (Thanks, Jerry!)
I added some Android.mk files that allows us to compile and
run a few simple unit tests.
Unit Test 1: The library compiles. (passes)
Unit Test 2: The test program links and runs. (passes)
Change-Id: Ib4c9554553de49645b5841b0bae889728cbfc8b1
