Changes as requested by daniel in merge feedback:

- change to get_slave_lag
- if then else
- chop comments 80 char wide

t/pt-table-checksum/samples/plugins/all_hooks.pm

@@ -26,9 +26,9 @@ sub after_replicate_check {
    print "PLUGIN after_replicate_check\n";
 }
  
-sub override_slavelag_check {
+sub get_slave_lag {
    my ($self, %args) = @_;
-   print "PLUGIN override_slavelag_check\n";
+   print "PLUGIN get_slave_lag\n";
    return sub { return 0; };
 }