Description:
------------
With specific big $max value, rand(0, $max) function returns unexpected, strange values. 

Test script creates an array with numbers of occurences rand(0, $max) % $n results. Expected result is an array with all values (almost) equal, with big $iter value.

But when $max is equal:
- getrandmax() * 2
- getrandmax() * 2 + 1
- getrandmax() * 2 + 2
returned array looks like:

array(16) {
  [0]=>
  int(0)
  [1]=>
  int(124837)
  [2]=>
  int(0)
  [3]=>
  int(125168)
  [4]=>
  int(0)
  [5]=>
  int(124687)
  [6]=>
  int(0)
  [7]=>
  int(125015)
  [8]=>
  int(0)
  [9]=>
  int(124685)
  [10]=>
  int(0)
  [11]=>
  int(125265)
  [12]=>
  int(0)
  [13]=>
  int(125077)
  [14]=>
  int(0)
  [15]=>
  int(125266)
}

When $max is equal:
- getrandmax() * 2 + 4
- getrandmax() * 2 + 6
- getrandmax() * 2 + 8
- getrandmax() * 2 + 10
- ...
distribution of counters looks very strange, like:

array(16) {
  [0]=>
  int(83187)
  [1]=>
  int(41787)
  [2]=>
  int(83074)
  [3]=>
  int(41420)
  [4]=>
  int(83377)
  [5]=>
  int(41756)
  [6]=>
  int(83319)
  [7]=>
  int(41941)
  [8]=>
  int(83469)
  [9]=>
  int(41925)
  [10]=>
  int(83327)
  [11]=>
  int(41544)
  [12]=>
  int(83287)
  [13]=>
  int(41528)
  [14]=>
  int(83098)
  [15]=>
  int(41961)
}

Probably, when $max is greater then getrandmax(), an error/notice should be generated.


Test script:
---------------
<?php

$iter = 1000000;
$max = getrandmax() * 2;
$n = 16;

$values = array_fill(0, $n, 0);

for ($i = 0; $i < $iter; $i++) {
        $values[rand(0, $max) % $n] += 1;
}

var_dump($values);

Expected result:
----------------
Expected results of test script is something similiar to:

array(16) {
  [0]=>
  int(62287)
  [1]=>
  int(62495)
  [2]=>
  int(62638)
  [3]=>
  int(62791)
  [4]=>
  int(62386)
  [5]=>
  int(62533)
  [6]=>
  int(62921)
  [7]=>
  int(62532)
  [8]=>
  int(62971)
  [9]=>
  int(62541)
  [10]=>
  int(62854)
  [11]=>
  int(61833)
  [12]=>
  int(62269)
  [13]=>
  int(62305)
  [14]=>
  int(62351)
  [15]=>
  int(62293)
}

when all values are close to each other.