Clean trailing white-space.

printbuf.h

@@ -15,7 +15,7 @@
 
 /**
  * @file
- * @brief Internal string buffer handing.  Unless you're writing a 
+ * @brief Internal string buffer handing.  Unless you're writing a
  *        json_object_to_json_string_fn implementation for use with
  *        json_object_set_serializer() direct use of this is not
  *        recommended.