swig-rb: Move the config path into a temp directory rather.

Previous code assumed that config in the current working directory could be
deleted and remade.  It worked fine but it's really not right.

* subversion/bindings/swig/ruby/test/util.rb:
  (SVNTestUtil.setup_default_variables): config_path should be in the temp path.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1597885 13f79535-47bb-0310-9956-ffa450edef68