Following up on r1619068, do not mention the removed SVN_ERR_RECURSIVE_LOCK
error in comments.  We no longer used checked mutexes, so this part of the
information is now outdated, and we just have to tell the reader about the
possible deadlock and about how we avoid it.

No functional change.

* subversion/tests/cmdline/svnadmin_tests.py
  (freeze_freeze, freeze_same_uuid): Update comments.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1619408 13f79535-47bb-0310-9956-ffa450edef68