Merge from Widevine repo of http://go/wvgerrit/71323
When running multithreaded tests, we need to make sure there are no other
OEMCrypto calls between OEMCrypto_Initialize and the installation of the test
keybox.
bug: 123319961
test: ran juce's threading test
Change-Id: Ibd8951c764f6538da4afa9ad146a6a72064eb13a