PHPCS: fixed php compatibility warning

[sreichel]

Fixes;

FILE: ...lts/magento-lts/app/code/core/Mage/Core/Helper/EnvironmentConfigLoader.php
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FOUND 2 ERRORS AFFECTING 2 LINES
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 71 | ERROR | list() will assign variable from left-to-right since PHP 7.0.
    |       | Ensure all variables in list() are unique to prevent unexpected
    |       | results. (PHPCompatibility.Lists.AssignmentOrder.Affected)
 78 | ERROR | list() will assign variable from left-to-right since PHP 7.0.
    |       | Ensure all variables in list() are unique to prevent unexpected
    |       | results. (PHPCompatibility.Lists.AssignmentOrder.Affected)
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Related Pull requeset:

• see New feature: override configurations with env variables #3863