* subversion/svnrdump/load_editor.c: Attempt to acquire a lock of   sorts before attempting to load. This also ensures that   pre-revprop-change is enabled before it's too late.
* subversion/svnrdump/load_editor.c: Attempt to acquire a lock of
  sorts before attempting to load. This also ensures that
  pre-revprop-change is enabled before it's too late.

  (get_lock): Add new function based on the corresponding function in
  svnsync/main.c. The locking operation can be described as attempting
  to change a dummy revprop in a delay-loop.

  (new_revision_record): Before doing anything else, call get_lock and
  release it at the end of the operations.



git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@998502 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion