swig-rb: Followup to r1597885, setup_tmp needs to be done before other things.

Not sure why this didn't cause problems with setup_repository which is also
under the tmp_path.  But it broke the config tests after I moved config_path
into the tmp_path in r1597885.

* subversion/bindings/swig/ruby/test/test_core.rb
  (SVNCoreTest.setup): setup_tmp removes the tmp path and recreates it.
    setup_config creates the default config files.  So without reversing
    the order trying to read the config files fails.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1597893 13f79535-47bb-0310-9956-ffa450edef68