From the Widevine CDM repository:
https://widevine-internal-review.googlesource.com/#/c/9183/
This adds unit tests for RSA signing with PKCS1 block type 1. It also
adds a reference implementation. This is part of OEMCrypto v9.
Change-Id: I2a40dbff65f6e09d75f16ae048499512f60c168d