PDO: Fix partial error return when using a encrypted connection

[TAINCER]

This fixes a problem with the original Zend1 repository we fixed in our fork a while ago. This only affects SSL MySQL connections, regular MySQL works fine.

How to reproduce (taken from the PHP bug report):

try {
        $pdo = new PDO(
                'mysql:host=localhost.localdomain;dbname=foo',
                'foo',
                'bar',
                array(
                        PDO::MYSQL_ATTR_SSL_KEY    => '/home/vagrant/newcerts/server-key.pem',
                        PDO::MYSQL_ATTR_SSL_CERT   => '/home/vagrant/newcerts/server-cert.pem',
                        PDO::MYSQL_ATTR_SSL_CA     => '/home/vagrant/newcerts/ca.pem',
                        PDO::MYSQL_ATTR_SSL_CIPHER => 'DHE-RSA-AES256-GCM-SHA384'
                )
        );
} catch (PDOException $e) {
        echo '# Actual:' . PHP_EOL;
        echo $e->getMessage() . PHP_EOL;
        echo '# Expected:' . PHP_EOL;
        echo $e->getMessage() . $e->getPrevious()->getMessage() . PHP_EOL;
}

Expected output

SQLSTATE[HY000] [2002] PDO::__construct(): SSL operation failed with code 1. OpenSSL Error messages: error:140830B5:SSL routines:ssl3_client_hello:no ciphers available

Actual output

SQLSTATE[HY000] [2002]

[TAINCER]

Hey, I've updated the description, I didn't mean to open the PR without it.

[glensc]

looks solid. i always hated mysql error messages being useless