Put JavaHL/jniwrapper's exception signal into the correct namespace.

[in subversion/bindings/javahl]
* native/jniwrapper/jni_javahl_exception.hpp: Removed.
* native/jniwrapper/jni_env.hpp: Do not include jni_javahl_exception.hpp.
  (Java::SignalExceptionThrown): replaces JavaHL::JavaException, and is
   no longer derived from std::exception.
  (Java::Env::throw_java_exception, Java::Env::check_java_exception):
   Update references to JavaHL::JavaException.

* native/jniwrapper/jni_base.cpp,
  native/jniwrapper/jni_exception.hpp,
  native/jniwrapper/jni_stack.hpp:
   Update all references to JavaHL::JavaException.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1543991 13f79535-47bb-0310-9956-ffa450edef68