Remove unnecessary NULL checks, part 4.

Finish up crypto, minus the legacy modules we haven't been touching much.

Change-Id: I0e9e1999a627aed5fb14841f8a2a7d0b68398e85
Reviewed-on: https://boringssl-review.googlesource.com/4517
Reviewed-by: Adam Langley <agl@google.com>
8 files changed