Tweak buildbot scripts after build rescheduling.

* svntest-bindings.cmd
  Don't test JavaHL.
  
* svntest-build-bindings.cmd
  Don't build JavaHL.
  
* svntest-build.cmd
  Allow adding targets via the config.
  
* svntests-javahl.cmd
  New javahl test script, based on the binding code.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1544134 13f79535-47bb-0310-9956-ffa450edef68