fix bound parameter references on SQL Anywhere and PHP 7

lib/Doctrine/DBAL/Driver/SQLAnywhere/SQLAnywhereStatement.php

@@ -59,6 +59,9 @@ class SQLAnywhereStatement implements IteratorAggregate, Statement
     /** @var resource The prepared SQL statement to execute. */
     private $stmt;
 
+    /** @var mixed[] The references to bound parameter values. */
+    private $boundValues = [];
+
     /**
      * Prepares given statement for given connection.
      *
@@ -108,6 +111,8 @@ class SQLAnywhereStatement implements IteratorAggregate, Statement
                 throw new SQLAnywhereException('Unknown type: ' . $type);
         }
 
+        $this->boundValues[$column] =& $variable;
+
         if (! sasql_stmt_bind_param_ex($this->stmt, $column - 1, $variable, $type, $variable === null)) {
             throw SQLAnywhereException::fromSQLAnywhereError($this->conn, $this->stmt);
         }