Locate a db_dump executable.
Locate a db_dump executable.

* subversion/tests/cmdline/svntest/objects.py
  (db_dump, dump_bdb): Add db_dump_name parameter.
  (locate_db_dump): New.
  (SvnRepository): Locate a db_dump executable and only attempt to
   dump if found.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@889733 13f79535-47bb-0310-9956-ffa450edef68

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