Implementation for RFCs: https://wiki.php.net/rfc/object_scope_prng

Overview:

• Provides PHP with a RNG implementation of object scope.
• Functions that use the existing internal MT RNG will now accept a new $rng argument.
  • shuffle()
  • str_shuffle()
  • array_rand()
• The following are implemented as built-in RNGs in this PR.
  • XorShift128+ (Modern PRNG)RNG\XorShift128Plus
  • MT19937 (PHP's internal MT compatibile) RNG\MT19937
  • OS (OS provided RNG generator) RNG\OS
• XorShift128Plus and MT19937 are serializable and can store state as a string.
• A few functions will be added
  • rng_bytes(): Generates a string of bytes of the specified length using RNG.
  • rng_int(): Generate a number using RNG, similar random_int() .
  • rng_next(): Generates 32bit raw random number using RNG.
  • rng_next64(): Generates 64bit raw random number using RNG.

Checklist:

• Check works on 64bit / 32bit architectures
• Check works on Windows
• Check correctly implemented __serialize() and __unserialize()
• Implement MT19973
• Add consistency tests 64bit / 32bit environments