Improve wrapper around OpenSSL RAND

[nbougalis]

High Level Overview of Change

Context of Change

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactor (non-breaking change that only restructures code)
• Tests (You added tests for code that already exists, or your new feature included in this PR)
• Documentation Updates
• Release

[intelliot]

Reopening because it looks like this was merged with zero reviews. @ximinez can you confirm that you reviewed this change as part of #4270?

If so, you can put an approval on this PR.

I know it has already been merged, but we'd like to confirm approval since this change (if not reverted) will be included in the 1.10 release.

[drlongle]

LGTM!

[scottschurr]

I'm not an expert with openSSL RAND, but these changes look reasonable to me.

[intelliot]

• There used to be a lock around OpenSSL code. OpenSSL internally implements a lock for this, so the other lock is no longer needed.
• Super minor performance improvement when OpenSSL randomness is used, which is not often.