We're a far cry from the good old days when we just read from /dev/urandom
without any fuss...
In particular, the threading logic is slightly non-trivial and probably worth
some basic sanity checks. Also write a fork-safety test, and test the
fork-unsafe-buffering path.
The last one is less useful right now, since fork-unsafe-buffering is a no-op
with RDRAND enabled (although we do have an SDE bot...), but it's probably
worth exercising the code in
https://boringssl-review.googlesource.com/c/boringssl/+/31564.
Change-Id: I14b1fc5216f2a93183286aa9b35f5f2309107fb2
Reviewed-on: https://boringssl-review.googlesource.com/31684
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
