There is an ambiguity in the use of the signature length in
OEMCrypto_GenerateRSASignature. If the pointer to the vector is null,
the function should set the length parameter to be the size of the
buffer needed.
This ambiguity has been clarified in the documentation: the
length returned should be the exact length of the buffer. It
will be corrected in a future release of Qualcomm's L1. However,
we are putting this change in both as a stop-gap and as a
belt-and-suspenders fix.
Bug: 8878371
Merge of https://widevine-internal-review.googlesource.com/#/c/5494/
from the Widevine CDM repository
Change-Id: I7574874884ca10da68d15674c971a565d015767d
3342e33143