service location plugin returning no addresses handled incorrectly

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: new

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@19399 dc483132-0cff-0310-8789-dd5450dbe970