Prior to 82639e6f we used thread-local data for the PRNG state. That
change switched to using a mutex-protected pool instead in order to save
memory in heavily-threaded applications.
However, the pool mutex can get extremely hot in cases where the PRNG is
heavily used. 8e8f2504 was a short-term work around, but supporting both
modes is overly complex.
This change moves back to the state of the prior to 82639e6f. The best
way to review this is to diff the changed files against '82639e6f^' and
note that the only difference is a comment added in rand.c:
https://paste.googleplex.com/4997991748337664
Change-Id: I8febce089696fa6bc39f94f4a1e268127a8f78db
Reviewed-on: https://boringssl-review.googlesource.com/c/34024
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
e6bf9065af
