o Minor features (performance, RNG):
    - Tor now constructs a fast secure pseudorandom number generator for
      each thread, to use for cases where performance is critical. This PRNG
      is based on AES-CTR, using a buffering construction similar to
      libottery and the (newer) OpenBSD arc4random() code.  It outperforms
      OpenSSL 1.1.1a's CSPRNG by roughly a factor of 100 for small outputs.
      Although we believe it to be cryptographically strong, we are only
      using it when necessary for reasonable performance. Implements tickets
      29023 and 29536.