Follow up to r1576277 and r1576283: Avoid creating empty temporary files with file contents in the Ev2 shims by introducing an internal flag that indicates that contents have changed.
Follow up to r1576277 and r1576283: Avoid creating empty temporary files with
file contents in the Ev2 shims by introducing an internal flag that indicates
that contents have changed.

* subversion/libsvn_delta/compat.c
  (struct change_node): Added boolean member 'contents_changed'.
  (process_actions): If we were notified about a contents change, but did
   not receive a delta (for example, during a status drive), return an empty
   in-memory stream and related empty checksum.
  (ev2_apply_textdelta): Flag that the contents have changed, and turn off
   the open-on-close flag on the lazy open of the text delta target stream.
   This avoids creating a temporary file on disk if no delta was received.
  (add_file_cb, alter_file_cb): Set the contents_changed flag along with
   the contents file path.
  (apply_change): Check both contents_changed and contents_abspath.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1576329 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion