Fix bug in example evbuffer cb code; found by "blindmatrix" on source…

…forge

Ref7_evbuffer.txt

@@ -882,7 +882,7 @@ void count_megabytes_cb(struct evbuffer *buffer,
 
 void operation_with_counted_bytes(void)
 {
- struct total_processed *tp = malloc(sizeof(tp));
+ struct total_processed *tp = malloc(sizeof(*tp));
  struct evbuffer *buf = evbuffer_new();
  tp->n = 0;
  evbuffer_add_cb(buf, count_megabytes_cb, tp);