Fix glossterm definition and use for AMQP

The glossentry for "Advanced Message Queuing Protocol (AMQP)" had a
newline in its glossterm, and the security-guide referenced
a short form which doesn't exist in the glossary.

This results in an error (and a missing glossary definition in the
output):

No definition found for <glossterm xmlns="http://docbook.org/ns/docbook"
xmlns:db="http://docbook.org/ns/docbook"
xmlns:xi="http://www.w3.org/2001/XInclude"
xmlns:xlink="http://www.w3.org/1999/xlink">AMQP</glossterm>

Fix: remove newline, use baseform to point to existing glossentry.

Change-Id: I18f64458c651ebc9696fc9f2f51b23af2600ef46