[php-src] Issue #21083: openssl_pkey_new() fails for EC keys on OpenSSL 3.6 - incorrectly requires private_key_bits

Issue: https://github.com/php/php-src/issues/21083
Author: ben182

### Description

### Description                                                                                                  
                                                                                                                   
  When using `openssl_pkey_new()` to generate EC keys with OpenSSL 3.6.0, the function incorrectly requires        
  `private_key_bits` even though this parameter is not relevant for elliptic curve keys (the key size is determined
   by the curve itself).                                                                                           
                                                                                                                   
  The workaround requires setting `private_key_bits` to 384, which is semantically incorrect for a 256-bit curve   
  like `prime256v1`. Setting it to 256 (the actual curve size) still fails.                                        
                                                                                                                   
  The OpenSSL CLI generates EC keys without issues (`openssl ecparam -name prime256v1 -genkey -noout`), suggesting 
  this is a PHP bindings issue.                                                                                    
                                                                                                                   
  **Environment:** PHP 8.5.2, OpenSSL 3.6.0                                                                        
                                                                                                                   
  ### Possible cause                                                                                               
                                                                                                                   
  OpenSSL 3.6 requires C-99 compilers (no longer ANSI-C), which changes integer behavior and sizes. Additionally,  
  OpenSSL 3.6 modified EC keygen error handling.                                                                   
                                                                                                                   
  The `private_key_bits` parameter should not apply to EC keys at all - the curve name (e.g., `prime256v1`)        
  implicitly defines the key size. It appears PHP's OpenSSL bindings incorrectly validate `private_key_bits` for EC
   keys when linked against OpenSSL 3.6.                                                                           
                                                                                                                   
  This same error has been reported in other projects:                                                             
  - https://community.librenms.org/t/new-install-openssl-pkey-new-private-key-length-must-be-at-least-384-bits-conf
  igured-to-0/22396                                                                                                
  - https://github.com/laravel/passport/issues/757                                                                 
                                                                                                                   
  ### References                                                                                                   
                                                                                                                   
  - https://github.com/web-push-libs/web-push-php/issues/445                                                       
  - https://github.com/openssl/openssl/blob/openssl-3.6.0/CHANGES.md                                               
  - https://github.com/openssl/technical-policies/pull/50 (C-99 requirement)                                       
                                                                                                                   
  ---                                                                                                              
                                                                                                                   
  The following code:                                                                                              
                                                                                                                   
  ```php                                                                                                           
  <?php                                                                                                            
  $key = openssl_pkey_new([                                                                                        
      'curve_name'       => 'prime256v1',                                                                          
      'private_key_type' => OPENSSL_KEYTYPE_EC,                                                                    
  ]);                                                                                                              
                                                                                                                   
  var_dump($key);                                                                                                  
  var_dump(openssl_error_string());                                                                                
                                                                                                                   
  Resulted in this output:                                                                                         
  bool(false)                                                                                                      
  string(63) "Private key length must be at least 384 bits, configured to 0"                                       
                                                                                                                   
  But I expected this output instead:                                                                              
  object(OpenSSLAsymmetricKey)#1 (0) {}                                                                            
  bool(false)

### PHP Version

```plain
PHP 8.5.2 (cli) (built: Jan 17 2026 23:04:39) (NTS clang 15.0.0)                                                 
  Copyright (c) The PHP Group                                                                                      
  Built by Laravel Herd                                                                                            
  Zend Engine v4.5.2, Copyright (c) Zend Technologies                                                              
      with Zend OPcache v8.5.2, Copyright (c), by Zend Technologies
```

### Operating System

macOS (Darwin 25.2.0)