#6767 using in_array rather than array_search

Ref: https://github.com/doctrine/doctrine2/pull/6767/files#r157355050

lib/Doctrine/ORM/Tools/SchemaTool.php

@@ -518,7 +518,7 @@ class SchemaTool
     private function gatherRelationsSql($class, $table, $schema, &$addedFks, &$blacklistedFks)
     {
         foreach ($class->associationMappings as $id => $mapping) {
-            if (isset($mapping['inherited']) && array_search($id, $class->identifier) === false) {
+            if (isset($mapping['inherited']) && ! \in_array($id, $class->identifier, true)) {
                 continue;
             }