Make FSX tests pass again.

* subversion/tests/libsvn_fs_x/fs-x-pack-test.c
  (pack_filesystem): Don't test for separate index files anymore.
                     That info is now part of the rev / pack file.

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1635375 13f79535-47bb-0310-9956-ffa450edef68