Try not to assign values through NULL pointers.

* subversion/bindings/javahl/native/RemoteSession.cpp
  (FileRevisionHandler::callback): Check the delta_handler and
   delta_handler_baton pointers before assigning values to the
   variables they refer to.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1519995 13f79535-47bb-0310-9956-ffa450edef68