Fixed small mistake I noticed too late: extension attachments don't use the same namespace as the FO extensions.

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@748990 13f79535-47bb-0310-9956-ffa450edef68

test/layoutengine/standard-testcases/afp-extension_1.xml

@@ -63,6 +63,6 @@
   <if-checks xmlns:if="http://xmlgraphics.apache.org/fop/intermediate"
         xmlns:afp="http://xmlgraphics.apache.org/fop/extensions/afp">
     <eval expected="this" xpath="//if:page-sequence/@afp:test-ignore"/>
-    <eval expected="MYMAP" xpath="//if:page-sequence/afp:invoke-medium-map/@name"/>
+    <eval expected="MYMAP" xpath="//if:page-sequence/afp:invoke-medium-map/@name" xmlns:afp="apache:fop:extensions:afp"/>
   </if-checks>
 </testcase>