On the 'move-tracking-2' branch: Print debugging messages only when
option -v/--verbose is given to svnmover.

* subversion/include/private/svn_editor3.h,
  subversion/libsvn_delta/compat3b.c
  (svn__set_verbose, svn__is_verbose): New.
  (SVN_DBG): Only print the message if svn__is_verbose() return true.

* subversion/libsvn_delta/compat3.c
  (SVN_DBG): Define as blank: we're not currently debugging this file.

* subversion/libsvn_ra/ra_loader.c
  (svn_ra_get_commit_editor_ev3): Only wrap an Ev1 debug editor if
    svn__is_verbose() return true.

* subversion/svnmover/svnmover.c
  (usage): Add '-v' option.
  (sub_main): Enable debugging when '-v' given.

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/move-tracking-2@1639691 13f79535-47bb-0310-9956-ffa450edef68