This was noticed by observing we had one line of missing test coverage
in polyval.c. CRYPTO_POLYVAL_update_blocks acts 32 blocks at a time and
all existing test vectors are smaller than that.
Test vector obtained by just picking random values and seeing what our
existing implementation did if I modified CRYPTO_POLYVAL_update_blocks
to consume many more blocks at a time. Then I fixed the bug and ensured
the answer was still the same.
Change-Id: Ib7002dbc10952229ff42a17132c30d0e290d4be5
Reviewed-on: https://boringssl-review.googlesource.com/13041
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>