Low-level hash 'final' functions cannot fail.

The SHA-2 family has some exceptions, but they're all programmer errors
and should be documented as such. (Are the failure cases even
necessary?)

Change-Id: I00bd0a9450cff78d8caac479817fbd8d3de872b8
Reviewed-on: https://boringssl-review.googlesource.com/4953
Reviewed-by: Adam Langley <agl@google.com>
3 files changed