The XSLT Saxon engine warns about some "Ambiguous rule matches".

Use priority to remove the ambiguity.

The only rational for choosing "3" and "4" for these priorities, is that "4" is related to <h4> tags, and 3=4-1 for the previous level.

Tested with the actual Xalan XSL engine:
   ./build.sh all
with and without the change.
Outputs are exactly the same.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1842165 13f79535-47bb-0310-9956-ffa450edef68