[php-src] Issue #21453: rand(), mt_rand(), and random_bytes() produce repeated dash characters

Issue: https://github.com/php/php-src/issues/21453
Author: Raven-Singularity

### Description

I was using the following code to produce a 4KiB random binary file:

```php

$Random_Key = "";

for ($Count = 0; $Count < 4096; $Count++) {
   $Random_Key .= chr(rand(0, 255));
}

file_put_contents("/tmp/testing.bin", $Random_Key);

<?php
```

I noticed that on most runs of the code, there were long sequences of dashes "---------" showing up on most runs of the code.  Sometimes there were no sequences of dashes, and this would carry on for numerous runs in a row.  But inevitably, the same code would again produce long sequences of dash characters.  I am viewing the binary file in Vim for ease of use on the terminal, which changes non-printable characters to <NN>.  There doesn't appear to be any other repeated sequences apart from dashes in any of the outputs.

First portion of output with repeating dashes:
```
Wý^HÀLÛ$^K0Õq<93>cmo]MY<93>äíø÷C<91><95>GÈ^[_^Hø^^<96>w={^B^A^S<93>¤<99>Æ^M<8a>1^_`<82>x¯<8b>>-------------------------^PKf^U7^Z|±ðhÌ^Z^Q»Æ^G^WþÝ<9f>^Ou-'ÍH+¼Ï* ^\<89>Ó^Cpmk8%ÏmOÉÁ+<83>í7ï­èè^X^\<97>^Lf§Uø1^_^PÈ2¯þùgÄZÌ^<92>´¹)3 ý!
```

Another portion with repeating dashes:
```
]äÈUÚzaÆ<94>Q<92><9a><89>Fb_Ý<<82>Ïîô^Y<88>Q·Ìñ<95>ô|:ë^AÖ>--------------------------^PâÅÁ^WØI8<8c><94>oëÂlS£HX^Wq<9d>ÁÑ^W<96>Q<9a><82>ªÂjG̳ê_Zío0<81>Xm<82>Å#jÌ0<87>¬^B<90>4Âahã\¦|<8c>v<95>ÇÙÔÄ*ñÝ>--^L<90>où^NJ©^NuÆ´Ö<87>h³S<87>OL<ÁÈýg^PW
```

Final portion with dashes repeating:
```
a>^TÊ£<95>^\>--'"pe~^\^Ln<90>@^Tû~UÕ3<91>>--------E<8c>e2P5ç:S%8Zgèue^[Vq<83>×5HÃ8eÅ<8a><80>Wº^C}$pö<8f>g
```

When the dashes problem is occurring, it usually appears more than once in the 4KiB of binary data.  On this same output file, there are a total of 3 sets of long dash sequences.  Possibly 5, as there are two other instances of "--" appearing above, which may or may not be random.  

But I expected this output instead:
I expect fairly random output, with no long sequence of dash characters.

Reading the page on `rand()` it says that `mt_rand()` should be used for better random numbers, and also says that `rand()` is an alias for `mt_rand()`.  I then found the `random_bytes()` function, which is supposed to produce cryptographically secure byte sequences -- but this function also produces the exact same sequences of dashes!

Again, not every time.  It happens for a while, then doesn't happen.

This code was being run via Nginx with PHP-FPM, so I decided to try it directly on the command line with php -r '...', and it had the same exact issue of dashes appearing... but then it stopped producing them after a dozen or so runs.  After this I wrote a Bash one-liner to run it repeatedly and check is the output file contained a sequence of more than 8 dashes in a row, and it didn't produce them even with thousands of iterations.  I don't know what triggers the dashes to appear or not appear, but they keep coming back without changing my code.  After testing on the command line, I went back to PHP-FPM where I had switched to using `random_bytes()`, and it immediately had the sequence of dashes I posted above (3 sets of dashes in the random bytes).  Almost every reload of the page it has the dashes.

When the problem occurs, there are most often 2 or 3 long sequences of dashes in a row.  For the length of dashes appearing in a row, I have noticed up to ~75 or so, which is definitely impossible to be random.

Has anyone ever seen long sequences of non-random bytes like this before?  But only at random, not every time?

Note: I am using Ubuntu 20.04.6 LTS running on Windows Subsystem for Linux.  On this platform it runs a patched Linux kernel (5.10.102.1-microsoft-standard-WSL2) that runs directly on top of Windows 10/11.  I have not noticed any other issues with random numbers on this WSL kernel.

### PHP Version

```plain
PHP 7.4.3-4ubuntu2.29

I just wrote this bug report, then got to this part that says PHP 7.4 is not a supported version for bug reports.  The version box should really be at the start of the bug report, so people don't waste their time writing a report only to find out it's for an unsupported version.  Sigh.  I will try to install PHP 8.x to see if the problem persists, but it's not easy to install on this version of Ubuntu LTS.

Has random_bytes() changed at all since PHP 7.4?  Were critical vulnerabilities found in that function related to dash characters repeating?
```

### Operating System

Ubuntu 20.04.6 LTS on Windows Subsystem for Linux