This was done just by grepping for 'size_t i;' and 'size_t j;'. I left
everything in crypto/x509 and friends alone.

There's some instances in gcm.c that are non-trivial and pulled into a
separate CL for ease of review.

Change-Id: I6515804e3097f7e90855f1e7610868ee87117223
Reviewed-on: https://boringssl-review.googlesource.com/10801
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: Adam Langley <agl@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>