Drop test tables only if exists, to prevent errors on clean database

(cherry picked from commit 56b225fe7cecb954b9166ce179201b3e493b48de)

tests/Zend/Test/PHPUnit/Db/Integration/MysqlIntegrationTest.php

@@ -57,8 +57,8 @@ class Zend_Test_PHPUnit_Db_Integration_MysqlIntegrationTest extends Zend_Test_PH
         );
 
         $this->dbAdapter = Zend_Db::factory('pdo_mysql', $params);
-        $this->dbAdapter->query("DROP TABLE foo");
-        $this->dbAdapter->query("DROP TABLE bar");
+        $this->dbAdapter->query("DROP TABLE IF EXISTS foo");
+        $this->dbAdapter->query("DROP TABLE IF EXISTS bar");
         $this->dbAdapter->query(
             'CREATE TABLE foo (id INT(10) AUTO_INCREMENT PRIMARY KEY, foo VARCHAR(255), bar VARCHAR(255), baz VARCHAR(255)) AUTO_INCREMENT=1'
         );