Do not constantly create objects in JavaHL's SVNUtil module.

[in subversion/bindings/javahl]
* src/org/apache/subversion/javahl/SVNUtil.java
  (SVNUtil.configLib, SVNUtil.diffLib, SVNUtil.propLib):
   New static members; each refers to one utility module instance.
   Replace all uses of "new *Lib" with the equivalent static instance.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1540923 13f79535-47bb-0310-9956-ffa450edef68