Define determine_locale() only if not already defined

[kingkero]

Using this library alongside php-stubs/wordpress-stubs will break PHPStan.

composer.json (partially) (php-stubs/wordpress-stubs is a dependency of php-stubs/woocommerce-stubs)

  "scripts": {
    "phpstan": "phpstan analyze"
  },
  "require-dev": {
    "paulthewalton/acf-pro-stubs": "^5.8",
    "php-stubs/woocommerce-stubs": "^3.8",
    "szepeviktor/phpstan-wordpress": "^0.5.0"
  }

phpstan.neon.dist (partially)

includes:
    # @see https://github.com/phpstan/phpstan/blob/master/conf/bleedingEdge.neon
    - phar://phpstan.phar/conf/bleedingEdge.neon
    # Include this extension
    - vendor/szepeviktor/phpstan-wordpress/extension.neon
parameters:
    level: max
    inferPrivatePropertyTypeFromConstructor: true
    autoload_files:
      - %currentWorkingDirectory%/vendor/php-stubs/woocommerce-stubs/woocommerce-stubs.php
      - %currentWorkingDirectory%/vendor/paulthewalton/acf-pro-stubs/acf-pro-stubs.php

Running phpstan analyze will then result in

➜ composer phpstan
> phpstan analyze
Note: Using configuration file .../phpstan.neon.dist.
PHP Fatal error:  Cannot redeclare determine_locale() (previously declared in .../vendor/php-stubs/wordpress-stubs/wordpress-stubs.php:89692) in .../vendor/paulthewalton/acf-pro-stubs/acf-pro-stubs.php on line 16212
Fatal error: Cannot redeclare determine_locale() (previously declared in .../vendor/php-stubs/wordpress-stubs/wordpress-stubs.php:89692) in .../vendor/paulthewalton/acf-pro-stubs/acf-pro-stubs.php on line 16212

This PR will solve this issue.

[kingkero]

Just realized the file is auto generated. Might look into this in the future.