Some of the complaints seem a bit questionable or their replacements
problematic, but not using strcat, strcpy, and strncpy is easy and
safer.

Change-Id: I64faf24b4f39d1ea410e883f026350094975a9b5
Reviewed-on: https://boringssl-review.googlesource.com/22125
Reviewed-by: Steven Valdez <svaldez@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>