AES Random number generator fixes.
AES Random number generator fixes.

 * Use CTR-AES256 with a random key + IV instead of CBC-AES128 with
   a random key + fixed IV.
 * Replaced a few useless memset calls with array initialization.
 * OPENSSL_cleanse the key/IV off the stack after initializing the DRBG.
 * Properly detect failure to initialize the DRBG.
 * Call `abort()` on EVP_EncryptUpdate failure in addition to spamming
   stderr.

dstebila/rlwekex,dstebila/rlwekex