Add a new-style, cached wrapper for the SubversionException class to JavaHL.'

* subversion/bindings/javahl/native/SubversionException.hpp,
  subversion/bindings/javahl/native/SubversionException.cpp: New files.

* subversion/bindings/javahl/native/jniwrapper/jni_class_cache.cpp
  (Java::ClassCache::ClassCache): Add initializer for the
   SubversionException generator class.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1539116 13f79535-47bb-0310-9956-ffa450edef68