This CL undoes the merge cc28abea0b by
TreeHugger that should not have gone to master. We re-enable a unit
tests that is required for OC MR1, but is not required for OC.
It also includes a minor change that allows the oemcrypto mock to be
built by an Android NDK:
Merge from Widevine repo of http://go/wvgerrit/24681
b/31458046
b/35141278
Change-Id: I8edc51504a16f1825ef765aeaff6f77f034f0362