Fix some PDO::MYSQL_* constants (wrongly described in PHP manual before 5.3.21)

INSTALL

@@ -14,7 +14,7 @@ REQUIREMENTS
 * PHP Version 5.2.1 or greater including
    - PCRE, DOM, JSON, XML, Session, Sockets (required)
    - PHP Data Objects (PDO) with driver for either MySQL, PostgreSQL or SQLite (required)
-     Note: MySQL database driver requires PHP 5.3 or newer.
+     Note: MySQL database driver requires PHP 5.3.7 or newer.
    - Libiconv, Zip (recommended)
    - Fileinfo, Mcrypt, mbstring (optional)
 * PEAR packages distributed with Roundcube or external:

program/lib/Roundcube/rcube_db_mysql.php

@@ -128,11 +128,11 @@ class rcube_db_mysql extends rcube_db
         $result = array();
 
         if (!empty($dsn['key'])) {
-            $result[PDO::MYSQL_ATTR_KEY] = $dsn['key'];
+            $result[PDO::MYSQL_ATTR_SSL_KEY] = $dsn['key'];
         }
 
         if (!empty($dsn['cipher'])) {
-            $result[PDO::MYSQL_ATTR_CIPHER] = $dsn['cipher'];
+            $result[PDO::MYSQL_ATTR_SSL_CIPHER] = $dsn['cipher'];
         }
 
         if (!empty($dsn['cert'])) {