Fix array-bounds crash in XMPPPubSub when parsing ping-response IQs

Crash occurs when id has only one component, and count is 0

Example:
<iq xmlns="jabber:client" id="3FA360E2-EB57-4F71-A645-183C53555773" type="result"></iq>
Merge pull request #147 from noa--/pullreq5

Fix array-bounds crash in XMPPPubSub when parsing ping-response IQs