* plugin-runner.c (add_to_char_array): Added "nonnull" attribute.
  (add_argument): Added "nonnull" attribute on the "arg" argument.
  (add_environment): Added "nonnull" attribute on the "def" argument.
  (print_out_password, free_plugin): Added "nonnull" attribute.
  (main/parse_opt): Added "nonnull" attribute on the "state" argument.
* plugins.d/mandos-client.c (perror_plus): Bug fix; restore errno
                                           after fprintf().
* plugins.d/password-prompt.c (fprintf_plus): New.
 (conflict_detection/is_plymouth, main/parse_opt): Added "nonnull"
                                                   attribute.
 (conflict_detection/is_plymouth, conflict_detection, main): Bug fix;
                                                             Call
                                                             error_plus()
                                                             instead
                                                             of
                                                             error().
  (main/parse_opt): Added "nonnull" attribute on the "state" argument.
* plugins.d/plymouth.c (exec_and_wait): Added "nonnull" attribute on
                                        the "path" and "argv"
                                        arguments.
  (is_plymouth): Added "nonnull" attribute.