Description:
------------
addServer() always returns true, regardless if a connection was made or not.

Reproduce code:
---------------
<?php

system('memcached -d -p 11211 -u nobody -c 64 -m 64 -P /var/run/memcached/11211');
system('memcached -d -p 11212 -u nobody -c 64 -m 64 -P /var/run/memcached/11211');
$memcache = new Memcache;
$res = $memcache->addServer('localhost', 11211);
var_dump ($res);
$res = $memcache->addServer('localhost', 11212);
var_dump ($res);
$res = $memcache->addServer('localhost', 11213);
var_dump ($res);

var_dump($memcache);
?>

Expected result:
----------------
bool(true)
bool(true)
bool(false)
object(Memcache)#1 (1) {
  ["connection"]=>
  resource(7) of type (memcache connection)
}

Actual result:
--------------
bool(true)
bool(true)
bool(true)
object(Memcache)#1 (1) {
  ["connection"]=>
  resource(7) of type (memcache connection)
}