Restructure the code in JavaHL that creates error messages from
svn_error_t chains, and expose error chains in the client notifications.

[in subversion/bindings/javahl/src/org/apache/subversion/javahl]
* ClientNotifyInformation.java
  (ClientNotifyInformation.serialVersionUID): Update serialization identity.
  (ClientNotifyInformation.errMsgStack): New private member.
  (ClientNotifyInformation.ClientNotifyInformation): Initialize errMsgStack.
  (ClientNotifyInformation.getErrMsgDetails): New accessor for errMsgStack.

[in subversion/bindings/javahl/native]
* JNIUtil.h (JNIUtil::makeSVNErrorMessage): Change signature.
  (JNIUtil::message_stack_item, JNIUtil::error_message_stack_t): Removed.
  (JNIUtil::assembleErrorMessage): Removed.
* JNIUtil.cpp (JNIUtil::makeSVNErrorMessage): Reimplement. Returns an
   error message and message stack without tracing info.
  (MessageStackItem, ErrorMessageStack): New types in namespace scope.
  (assemble_error_message): New, replaces JNIUtil::assembleErrorMessage.
  (construct_Jmessage_stack): Use the new namespace-scope types.
  (JNIUtil::handleSVNError): Use makeSVNErrorMessage to get the messages.
  (JNIUtil::assembleErrorMessage): Removed.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1531466 13f79535-47bb-0310-9956-ffa450edef68