/usr/share/php/Symfony/Component/Config/Definition/Builder/ is in php-symfony-config 2.3.21+dfsg-4+deb8u3.
This file is owned by root:root, with mode 0o755.
..
/usr/share/php/Symfony/Component/Config/Definition/Builder/ArrayNodeDefinition.php
/usr/share/php/Symfony/Component/Config/Definition/Builder/BooleanNodeDefinition.php
/usr/share/php/Symfony/Component/Config/Definition/Builder/EnumNodeDefinition.php
/usr/share/php/Symfony/Component/Config/Definition/Builder/ExprBuilder.php
/usr/share/php/Symfony/Component/Config/Definition/Builder/FloatNodeDefinition.php
/usr/share/php/Symfony/Component/Config/Definition/Builder/IntegerNodeDefinition.php
/usr/share/php/Symfony/Component/Config/Definition/Builder/MergeBuilder.php
/usr/share/php/Symfony/Component/Config/Definition/Builder/NodeBuilder.php
/usr/share/php/Symfony/Component/Config/Definition/Builder/NodeDefinition.php
/usr/share/php/Symfony/Component/Config/Definition/Builder/NodeParentInterface.php
/usr/share/php/Symfony/Component/Config/Definition/Builder/NormalizationBuilder.php
/usr/share/php/Symfony/Component/Config/Definition/Builder/NumericNodeDefinition.php
/usr/share/php/Symfony/Component/Config/Definition/Builder/ParentNodeDefinitionInterface.php
/usr/share/php/Symfony/Component/Config/Definition/Builder/ScalarNodeDefinition.php
/usr/share/php/Symfony/Component/Config/Definition/Builder/TreeBuilder.php
/usr/share/php/Symfony/Component/Config/Definition/Builder/ValidationBuilder.php
/usr/share/php/Symfony/Component/Config/Definition/Builder/VariableNodeDefinition.php