Fix 'help' command for the svn-mergeinfo-normalizer tool.

* tools/client-side/svn-mergeinfo-normalizer/svn-mergeinfo-normalizer.c
  (sub_main): Make 'help <subcommand>' work by keeping the target list
              untouched for the 'help' command.

* tools/client-side/svn-mergeinfo-normalizer/help-cmd.c
  (svn_min__help): Update general help string to name the correct tool.

Found by: philip

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/svn-mergeinfo-normalizer@1643143 13f79535-47bb-0310-9956-ffa450edef68
* tools/client-side/svn-mergeinfo-normalizer/svn-mergeinfo-normalizer.c
  (sub_main): Remove unused 'undo' command.


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/svn-mergeinfo-normalizer@1643144 13f79535-47bb-0310-9956-ffa450edef68