On the 'move-tracking-2' branch: Add argument checking in 'svnmover'.

* subversion/svnmover/svnmover.c
  (VERIFY_REV_SPECIFIED,
   VERIFY_REV_UNSPECIFIED,
   VERIFY_EID_NONEXISTENT,
   VERIFY_EID_EXISTS): New macros.
  (execute): Use them.


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/move-tracking-2@1636650 13f79535-47bb-0310-9956-ffa450edef68