Add newline at the end of header generated by generate-wait_event_types.pl

The header file wait_event_types.h was generated without a newline at
its end, which was inconsistent with all the other things generated
automatically.

Per offline gripe from Nathan Bossart.

src/backend/utils/activity/generate-wait_event_types.pl

@@ -185,7 +185,7 @@ if ($gen_code)
 		printf $c "}\n\n";
 	}
 
-	printf $h "#endif                          /* WAIT_EVENT_TYPES_H */";
+	printf $h "#endif                          /* WAIT_EVENT_TYPES_H */\n";
 	close $h;
 	close $c;