cluster_fatal() exit code should not indicate success.

cluster_fatal() exit code should not indicate success.

cluster_fatal() logs a fatal event and then exits with 0.  This seems
wrong.  Sometimes command like "net" use this code and return
incorrect empty output but then exit with 0.

This simply changes the exit code to 1.

Signed-off-by: Martin Schwenke <martin@meltin.net>