Description:
------------
Segfaults when ID is not valid

Test script:
---------------
<?php
require_once "bootstrap.inc";

$options = array
(
    'hostname' => SOLR_SERVER_HOSTNAME,
    'login'    => SOLR_SERVER_USERNAME,
    'password' => SOLR_SERVER_PASSWORD,
    'port'     => SOLR_SERVER_PORT,
    'path'     => SOLR_SERVER_PATH
);

$client = new SolrClient($options);

try {
	$client->deleteByIds(array(0));	
} catch (SolrIllegalArgumentException $e) {
	echo sprintf("Exception %d: %s", $e->getCode(), $e->getMessage()). PHP_EOL;
}

try {
	$client->deleteByIds(array('334455', ''));
} catch (SolrIllegalArgumentException $e) {
	echo sprintf("Exception %d: %s", $e->getCode(), $e->getMessage()). PHP_EOL;
}

Expected result:
----------------
Exception 4000: Id number 1 is not a valid string
Exception 4000: Id number 2 is not a valid string

Actual result:
--------------
Segmentation fault (core dumped)