This was specific to some old software on the test machine. Shrinking
the critical section to not cover getrandom is probably worthwhile
anyway though, so keep it around but make the comment less scary.
Change-Id: I8c17b6688ae93f6aef5d89c252900985d9e7bb52
Reviewed-on: https://boringssl-review.googlesource.com/16992
Reviewed-by: Adam Langley <agl@google.com>