Follow-up to r1589048: update callers of deprecated svn_repos_open2().

* subversion/libsvn_repos/authz.c
* subversion/libsvn_repos/config_pool.c
* subversion/svnadmin/svnadmin.c
* subversion/svnlook/svnlook.c
* subversion/tests/libsvn_repos/repos-test.c
* subversion/tests/svn_test_fs.c
* tools/server-side/svn-populate-node-origins-index.c
* tools/server-side/svn-rep-sharing-stats.c
* tools/server-side/svnauthz.c
  (authz_retrieve_config_repo, find_repos_config, open_repos, 
   get_ctxt_baton, test_repos_fs_type, svn_test__create_repos,
   build_index, process, get_authz_from_txn): Use svn_repos_open3()
   instead of svn_repos_open2().


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1589421 13f79535-47bb-0310-9956-ffa450edef68