DERBY-6213: Deprecate support for Java 5 and CDC

- Revive build target for SqlXmlUtil to ensure that it always includes
  the org.w3c.dom.xpath interfaces on the compile classpath.

- Update SqlXmlUtil.java so that no warnings are printed during
  compilation.

- Remove code that's only used on Java 1.4 and CDC.

git-svn-id: https://svn.apache.org/repos/asf/db/derby/code/trunk@1481187 13f79535-47bb-0310-9956-ffa450edef68