Make DAV and SVN tests skip some svnauthz tests.

I'll be refactoring them so not so many tests should get skipped but
for now make the build bots happy.

* subversion/tests/cmdline/svnauthz_tests.py
  (svnauthz_validate_test, svnauthz_accessof_test, svnauthz_accessof_is_test,
   svnauthz_compat_mode_test): Skip these tests unless doing an ra local test.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1438289 13f79535-47bb-0310-9956-ffa450edef68