Try to unbreak the JavaHL tests, again; this time with an
actually relevant change.

[in subversion/bindings/javahl/native]
* OperationContext.cpp
  (OperationContext::openTunnel): Remember the context object.

* org_apache_subversion_javahl_util_TunnelChannel.cpp
  (Java_org_apache_subversion_javahl_util_RequestChannel_nativeRead,
   Java_org_apache_subversion_javahl_util_ResponseChannel_nativeWrite):
    Do not throw exceptions for invalid file descriptors, since
    get_file_descriptor already does that.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1533864 13f79535-47bb-0310-9956-ffa450edef68