pull up r19399 from trunk

pull up r19399 from trunk

 r19399@cathode-dark-space:  raeburn | 2007-04-05 16:22:28 -0400
 ticket: new
 subject: service location plugin returning no addresses handled incorrectly

 If a locate plugin (e.g., the Python sample plugin and script, when
 given realm BOBO.MIT.EDU) returns no error but no addresses, the library
 won't report an error, but will try to make contact, and eventually
 crash with a null pointer dereference.

 Fix: If a plugin returns a value other than PLUGIN_NO_HANDLE, including
 success, continue into the code that checks for an empty address list.

ticket: 5509
version_fixed: 1.6.1

git-svn-id: svn://anonsvn.mit.edu/krb5/branches/krb5-1-6@19416 dc483132-0cff-0310-8789-dd5450dbe970