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.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion